,transcriber ,note ,text emphasis is denoted as3 ,italics and ,bold4 ,,poison-ivy ,,poison-oak and ,,poison sumac ,,identification ,,precautions ,,eradication ,farmers' ,bulletin ,no4 #aigb ,u4 ,s4 ,,department ,,of ,,agriculture ,,poison-,,ivy1 poison-oak1 and poison sumac remind most people of painful experiences to be avoided1 yet many do not know any one of the offending plants or their equally poisonous relatives4 ,learning to recognize them on sight is relatively easy1 especially by examining the distinctive identifying characters described in the pictures and legends of this bulletin4 ,there is then a good chance to avoid them or1 if one must work among them1 to take preventive measures to escape poisoning4 ,these plants are very common throughout the ,united ,states4 ,they are found in fields and woods1 along fence rows1 rock walls1 and hedges1 in lawns and gardens1 and even sometimes vining on houses4 ,usually in any one locality it is necessary to be certain of the identity of only two or three of them4 ,maps show at a glance where they are likely to be found4 ,frequent observation and recognition of the plants as they are encountered almost daily is the best way to become poison-oak or poison-ivy conscious4 ,nonpoisonous sumacs are easily distinguished from the poisonous species by the seed heads and leaves4 ,the old proverb1 an ounce of prevention is worth a pound of cure1 is good advice to everyone1 particularly as regards ivy-poisoning4 ,previous escape is not proof of immunity when conditions are right1 and after poisoning occurs there is no quick cure known4 ,some relief may be obtained and recovery hastened by use of some of the tested remedies4 ,in case of severe poisoning a physician should be consulted4 ,poison-ivy and other poisonous plants growing in grounds frequented by people should be eradicated4 ,in some places this can be done by careful grubbing4 ,in others weed-killing chemicals may be better and more certainly would avert poisoning for most of us4 ,this bulletin supersedes ,farmers' ,bulletin #aaff1 ,poison ,ivy and ,poison ,sumac and ,their ,eradication4 ,washington1 ,d4 ,c4 ,issued ,august #aide ,,poison-,,ivy1 ,,poison-,,oak1 ,,and ,,poison ,,sumac3 ,,identification1 ,,precautions1 ,,eradication ,by ,donald ,m4 ,crooks1 principal horticulturist1 ,division of ,tobacco1 ,medicinal1 and ,special ,crops1 and ,leonard ,w4 ,kephart1 senior agronomist1 ,division of ,cereal ,crops and ,diseases1 ,bureau of ,plant ,industry1 ,soils and ,agricultural ,engineering1 ,agricultural ,research ,administration ,contents ,page ,a widespread menace to health #a ,forms of poison-ivy and poison-oak #b ,common poison-ivy #b ,oakleaf poison-ivy #i ,western poison-oak #i ,poison sumac #af ,confusion of poisonous and harmless sumacs #ai ,introduced poisonous sumac and related species #ba ,poisoning #ba ,precautions against poisoning #bb ,treatment for poisoning #bc ,eradication of plants #be ,chemical weed killers #be ,eradication by mechanical means #be ,a ,,widespread ,,menace ,,to ,,health ,,every year sees many adults1 and especially children1 accidentally poisoned from contact with plants that they did not know were harmful4 ,had the sufferers known how to detect poisonous plants they could have avoided them and escaped the painful experience of severe skin inflammations and water blisters4 ,very few persons have a sufficient degree of immunity to protect them from poisonous plants1 and many do not recognize them in the various forms that they assume in different parts of the country4 ,one or more kinds of poison-ivy--common poison-ivy1 oakleaf poison-ivy1 and western poison-oak--occur in abundance in almost every part of the ,united ,states4 ,poison sumac is of more limited distribution and occurs chiefly east of the ,mississippi ,river1 usually in swampy regions4 ,poisoning by these plants is largely preventable4 ,a knowledge sufficient to identify them in their various forms is easily gained by anyone who will make a study of pictures and general descriptions and train himself by a little diligent practice to observe the plants in his locality4 ,it is important to become poison-oak or poison-ivy conscious4 ,this can be accomplished only by learning to know the plants by repeated experience in observing them in their various forms4 ,persons who learn both to know and to avoid the plants can save themselves much inconvenience and discomfort4 ,the simple means of learning to recognize them will pay big dividends4 ,it is the first step to the prevention of poisoning and to the eradication of the pests from private grounds and public places4 ,the most effective method of prevention is to eradicate the plants1 and wherever possible this should be done4 ,they should not be allowed to grow in lawns or gardens1 with ornamental shrubbery1 or on houses4 ,communities should not countenance the growth of poison-ivy or poison-oak in school grounds1 on public roadways1 or in parks1 especially those frequented by children4 ,the cost of medical aid for one season in treating pupils using an ivy-infested schoolyard is likely to be more than that of eradicating the plants1 to say nothing of the suffering and inconvenience they may cause4 ,,forms ,,of ,,poison-,,ivy ,,and ,,poison-,,oak ,poison-ivy and poison-oak are known by a number of local names1 and several different kinds of plants are called by these names4 ,the plants exhibit a good deal of variation throughout the ,united ,states1 so much so that even technical botanists cannot agree on the number of species and names that should be applied to them4 ,they grow in the form of 7#a7 woody vines attached to trees or objects for support1 7#b7 trailing shrubs mostly on the ground1 or 7#c7 erect woody shrubs entirely without support4 ,they may flourish in the deep woods1 where soil moisture is plentiful1 or they may be found in very dry soil on the most exposed hillsides4 ,the plants are most frequently abundant along old fence rows and edges of paths and roadways1 and they ramble over rock walls and climb posts or trees to considerable heights4 ,they often grow with other shrubs or vines in such ways as to escape notice4 ,the leaf forms among plants or even on the same plant are as variable as the habit of growth2 however1 the leaves always consist of three leaflets4 ,the old saying1 ,leaflets three1 let it be1 is a reminder of this consistent leaf character but may lead to undue suspicion of some harmless plant4 ,only one three-parted leaf leads off from each node on the stem4 ,the leaves never occur in pairs along the stem4 ,the wide range in habit of growth of plants and leaf types may be noted from a glance at the several pictures of plants and leaves4 ,the flowers and fruit are always in clusters on slender stems that originate in the axis of the leaves along the side of the smaller branches4 ,the fruits usually have a white1 waxy appearance and ordinarily are not hairy1 but may be so in some forms4 ,the plants do not always flower and bear fruit4 ,the white or cream-colored clusters of fruit1 when they occur1 are significant identifying characters1 especially at the season after the leaves have fallen4 ,for convenience1 these plants are discussed in this bulletin under three divisions3 7#a7 ,common poison-ivy1 7#b7 oakleaf poison-ivy1 and 7#c7 ,western poison-oak4 ,a technical botanist would recognize many species of plants in what are included as the common poison-ivy1 and anyone will recognize that various forms occur within this grouping4 ,,common ,,poison-,,ivy ,some form of the common poison-ivy may be found in almost every part of the country but the extreme ,west4 ,the shaded area on the map in figure #a shows the extensive range where some form of poison-ivy is likely to be found4 ,the plant is known by various local names--poison-ivy1 threeleaf ivy1 poison creeper1 climbing sumac1 poison-oak1 markweed1 piery1 and mercury4 ,the most widespread form is classified by botanists under the botanical name of ,rhus radicans or varieties of it2 however1 many of the variations are sometimes given other botanical names4 ,the common poison-ivy may be considered as a vine in its most typical growth habit4 ,figure #a4--,the shaded part shows the extensive area where some form of the common poison-ivy is likely to be found4 ,other forms also may occur in parts of the same region4 ,figure #b4--,large poison-ivy vine growing on a tree for support4 ,this is the usual form of the common poison-ivy in wooded areas4 ,figure #c4--;,a1 ,common poison-ivy growing in a hedge and on a shade tree on the edge of a lawn4 ,b1 ,typical vine1 showing leaves and the roots that attach it to the tree4 ,the vining type most often occurs in wooded areas 7fig4 #b71 where it depends upon trees for support4 ,vines often grow for many years1 becoming several inches in diameter and quite woody4 ,slender vines may run along the ground1 mixed with shrubbery1 or take support from a large or small tree4 ,that a plant growing along the edge of a lawn and into the shrubbery may be quite inconspicuous as compared with a vine climbing on a lawn tree is shown in figure #c4 ,the vine readily develops roots when in contact with the ground or with any object that will support it4 ,when the vines grow on trees these aerial roots attach the vine securely 7 fig4 #c4 ,b74 ,a rank growth of these roots often causes the vines on trees to have the general appearance of a fuzzy rope1 which sometimes serves a good purpose for identification4 ,the vines and roots apparently do not cause injury to the tree except where growth may be sufficient to cover the supporting plant and exclude sunlight or break the plant from excessive weight4 ,the vining nature of the plant makes it well adapted to climbing over stone walls or on brick and stone houses4 ,the fact that poison-ivy often becomes mixed in with ornamental shrubbery and vines often results in its cultivation as an ornamental vine by people who do not recognize the plant4 ,an ivy plant growing on a house1 as is shown in figure #d1 is often prized by an unsuspecting owner4 ,the vine is attractive and quite effective as an ornamental1 but such use should not be tolerated1 as it most certainly will result in cases of accidental poisoning and serve as propagating stock for more poison-ivy in the vicinity4 ,figure #d4--;,common poison-ivy growing on side of house with ornamental shrubs4 ,this accidental or intentional use of the attractive vine may lead to many cases of accidental poisoning4 ,figure #e4--;,common poison-ivy growing along fence row4 ,in open sunlight and over some large areas it is more of a shrub than a vine4 ,figure #d4--;,common poison-ivy growing on side of house with ornamental shrubs4 ,this accidental or intentional use of the attractive vine may lead to many cases of accidental poisoning4 ,when poison-ivy becomes mixed in with other vines it is quite difficult to detect except by one who has carefully trained himself in observing and recognizing the plant4 ,also1 some other vines and young plants resemble poison-ivy in many respects4 ,the ,virginia creeper and some forms of the ,boston ivy are often confused with it4 ,the ,virginia creeper can always be recognized by its five leaflets radiating from one point of attachment1 as compared with the three leaflets of poison-ivy arranged in the same manner4 ,the ,boston ivy with three leaflets is sometimes difficult to detect2 however1 as a rule not all the leaves on the plant will be divided into three leaflets4 ,by studying a large number of the leaves it is usually possible to detect on every ,boston ivy plant some leaves that have only one deeply lobed blade or leaflet1 while the poison-ivy always has the three leaflets4 ,a number of other plants are easily confused with poison-ivy4 ,no specific rule can be observed that will easily rule out all possibility of confusion4 ,the best policy is to learn through practiced observation to know poison-ivy on sight and then to make the determination from observation of all parts of the plant1 and never to judge from a single leaf or part4 ,figure #f4--,leaves of common poison-ivy1 about half natural size4 ,these may occur on the same or different plants3 ,a1 ,b1 ,c and ,f1 less common2 ,d1 with even margins1 the most common and generally recognized form2 ,e1 with lobed margins1 nearly nearly as often seen as the shape in ,d4 ,figure #g4--;,common poison-ivy vine with clusters of flowers in the axis of each leaf4 ,common poison-ivy in full sunlight along fence rows or in open fields grows more in the form of a shrub than a vine4 ,in some localities the common form is a low-growing shrub from #f to #cj inches in height4 ,this form1 as well as the vining type1 usually has a rather extensive horizontal system of rootstocks or stems at or just below the ground level4 ,the vining form under some conditions later becomes a shrub4 ,plants of this type are shown in figure #e1 where the vine1 supported on the fence1 has extended upright stems that are shrublike4 ,in some localities the growth form over a wide range is consistently either a vine or a shrub type1 while in others what seems to be the same species may produce either vines or shrubs4 ,the leaves of the common poison-ivy are extremely variable1 the three leaflets being the only constant character4 ,it is impossible to describe the great range of variation in the shape or lobing of the leaflets4 ,a study of the leaf patterns1 especially the six shown in figure #f1 will give a fair range of types1 although other forms may be found4 ,one plant may have a large variety of forms of leaves or it may have all leaves of about the same general character4 ,the most common type of leaf having leaflets with even margins is shown in figure #f1 ,d1 and one with leaflets having slightly lobed margins is shown in figure #f1 ,e4 ,the other forms shown in figure #f are not quite so widespread1 but may be the usual type throughout some areas4 ,figure #h4--;,common poison-ivy1 about natural size3 ,a1 ,flowers2 ,b1 mature fruit4 ,most of the vines or shrubs of poison-ivy produce some flowers that are always in clusters arising on the side of the stem immediately above a leaf4 ,the flowers are rather inconspicuous among the leaves1 as may be noted in figure #g1 but they are in quite distinct clusters1 as shown in figure #h1 ,a4 ,frequently the flowers do not develop or are abortive and no fruit is produced4 ,when fruits do develop they serve as a positive way of identifying the plant4 ,the berries are not easily confused with the fruits of other plants4 ,they are white and waxy in appearance and have rather distinct lines marking the outer surface1 as the segments appear in a peeled orange4 ,these lines may be noted in figure #h1 ,b1 which shows dense clusters of mature fruit about natural size4 ,some forms of the poison-ivy have the fruit covered with fine hair1 giving it a kind of downy appearance2 however1 in the more common form the fruits are entirely smooth4 ,the fruit is especially helpful in identifying plants late in fall1 in winter1 and early in spring1 when the leaves are not present4 ,figure #i4--,the shaded area is the region where the eastern oakleaf form of poison-ivy is likely to occur4 ,other forms also may be in the same region4 ,,oakleaf ,,poison-,,ivy ,of the several kinds of poison-ivy1 the oakleaf form occurring in the ,eastern and ,southern ,states is more distinctive than some other types4 ,some people know it as oakleaf ivy while others call it poison-oak1 a name more commonly used for the western species discussed later4 ,botanists have not always agreed upon the scientific name to be applied to this form2 however1 they now use the name ,rhus toxicodendron4 ,some botanists have used the ,latin names ,r4 quercifolia1 while others used the name ,toxicodendron quercifolium1 both of which are more descriptive of the oakleaf form1 as the generic name of the oak is ,quercus4 ,the area where the oakleaf form may occur1 from ,new ,jersey to ,texas1 is outlined in the map shown in figure #i4 ,the common poison-ivy also occurs in some form throughout many parts of this same area4 ,the oakleaf poison-ivy usually does not climb as a vine1 but occurs as a low-growing shrub4 ,stems are usually upright in their general growth habit1 as they appear in figure #aj4 ,the shrubs usually have rather slender branches1 often covered with a fine pubescence that gives the plant a kind of downy appearance4 ,the leaflets occur in threes1 as in other ivy1 but are lobed1 somewhat on the general plan of the leaves of some kinds of oak4 ,the middle leaflet usually is lobed somewhat alike on both margins and very much resembles a small oak leaf1 while the two lateral leaflets are often irregularly lobed4 ,the leaves shown in figure #aa are a common form4 ,the lighter color on the under side of one of the leaves 7fig4 #aa1 ,a7 is due to the pubescence1 or fine hairs1 on the surface4 ,the range in size of leaves varies considerably1 even on the same plant2 the leaf shown in figure #aa1 ,b1 however1 is about natural size4 ,the fruit of oakleaf poison-ivy has the same general appearance as the fruit of common poison-ivy shown in figure #h1 although the individual fruits and stems are often pubescent1 while most of the other forms have a waxy1 smooth1 cream-colored fruit4 ,figure #aj4--;,eastern oakleaf poison-ivy shrub4 ,the upright growth as a low shrub is common4 ,the three parts of each leaf somewhat resembles an oak leaf4 ,the gall formations that cause wartlike protuberances are common on all species4 ,figure #aa4--;,eastern oakleaf poison-ivy3 ,a1 ,leaves1 showing upper deep green surface and lower lighter colored surface4 ,b1 ,single leaf1 about natural size4 ,the terminal leaflet more nearly resembles an oak leaf than the two lateral leaflets4 ,,western ,,poison-,,oak ,the western poison-oak 7,rhus diversiloba7 of the ,pacific ,coast ,states is usually known as poison-oak1 but is occasionally referred to as poison-ivy or yeara4 ,it is likely to be found in the region designated by shading in figure #ab1 and from central ,oregon northward through ,washington may be growing intermixed with common poison-ivy4 ,the term poison-oak is a misnomer1 as this species is in no way related to the oak but is related to poison-ivy4 ,anyone familiar with either of these plants in their several forms will likely recognize the other1 both as plants to be avoided4 ,figure #ab4--,the shaded area is the region where the western poison-oak is likely to occur4 ,other forms may also be in the same region4 ,the most common growth habit of the western poison-oak is in the form of a rank upright shrub with many small woody stems rising from the ground4 ,it frequently grows in great abundance along roadsides 7see fig4 #af7 and in uncultivated fields or on abandoned land4 ,sometimes western poison-oak attaches itself to upright objects for support and takes more or less the form of a vine4 ,a plant of this type is shown in figure #ac1 where it is growing on a telephone pole by the roadside4 ,it may be noted even in this case that the tendency is for individual branches to continue an upright growth rather than become entirely dependent upon other objects for support4 ,in some areas1 especially in woodland1 poison-oak may grow principally as a vine4 ,areas have been noted where #gj to #hj percent of the trees leaves and flowers4 in a wooded area support vines running more than #be or #cj feet in height1 although the most common form of the plant is the shrub4 ,figure #ac4--,western poison-oak on a telephone pole4 ,this vine form is not uncommon1 especially on trees in woods4 ,figure #ad4--,western poison-oak3 ,upright shrub1 with fruit1 growing in open pasture field4 ,figure #ae4--,western poison-oak1 showing common leaf types3 ,a1 ,the more common leaves with irregular margins2 ,b1 less typical1 although not uncommon1 leaves with even margins4 ,figure #af4--,western poison-oak growing alongside roadside4 ,this rank shrubby growth is typical for most localities4 ,figure #ag4--,western poison-oak1 showing common leaf types3 ,a1 ,leaves with thick leathery appearance2 ,b1 leaves irregular in shape with much-curled or distorted surfaces2 ,c1 branch1 with leaves and flowers4 ,in open pasture fields western poison-oak usually grows in spreading clumps from a few feet to several feet tall 7figs4 #ad and #af74 ,where it develops extensively it greatly reduces the area for grazing and becomes a serious menace to most people who frequent the area or attend cattle that come in contact with the plants while grazing4 ,figure #ah4--,western poison-oak3 ,a1 ,top of shrub1 with leaves and fruit2 ,b1 clusters of fruit after leaves have fallen4 ,low-growing plants1 especially those exposed to full sunlight1 are often quite woody and show no tendency for vining4 ,low-growing plants with woody stems are common in pasture areas or along roadsides4 ,livestock in grazing do not invade the poison-ivy shrub1 and as a rule these plants continue to spread both by root-stock and seed4 ,as in other ivy the leaves consist of three leaflets with much irregularity in the manner of lobing1 especially of the two lateral leaflets4 ,the ,latin name dirersiloba refers to the irregularity occurring in the shapes of the leaves on different plants and on the same plant or even irregularity in the lobing of leaflets of the same leaf4 ,sometimes lobes occur on both sides of a leaflet1 thus giving it somewhat the semblance of an oak leaf4 ,the middle or terminal leaflet is more likely to be lobed on both sides and resembles an oak leaf more than the other two4 ,a study of the leaves shown in figures #ae and #ag shows the variation in lobing4 ,some plants may have leaflets with an even margin and no lobing whatsoever1 as those in figure #ae1 ,b4 ,the surface of the leaves is usually glossy and uneven1 so that they have a thick leathery appearance4 ,figure #ai4--;,a large poison sumac shrub about #ae feet tall1 growing on the edge of a swamp4 ,the flowers are borne in clusters on slender stems diverging from the axis of the leaf1 as may be noted in figure #ag1 ,c4 ,the individual flowers are greenish white and about one-fourth inch across4 ,the cluster of flowers matures into greenish or creamy-white berrylike fruits about mid-,october4 ,these are about the size of small currants and are much like other poison-ivy fruits1 having a smooth greenish-white glossy surface striped somewhat like the segments of a peeled orange4 ,many plants bear no fruit1 although others produce it in abundance1 as shown in figure #ah1 ,a4 ,the fruits are not always spherical1 but sometimes have a somewhat flattened appearance1 as is shown in figure #ah1 ,b4 ,they remain on the plants throughout fall and winter and are quite helpful in identifying poison-oak in seasons after the leaves have fallen4 ,figure #bj4--,the shaded area shows the region where poison sumac is likely to occur in bogs or swamps1 although isolated plants are sometimes found in dry soil4 ,,poison ,,sumac ,poison sumac grows as a coarse woody shrub or small tree 7fig4 #ai7 and never in the vinelike form of its poison-ivy relatives4 ,this plant is known also as swamp sumac1 poison elder1 poison ash1 poison dogwood1 and thunderwood4 ,it does not have variable forms1 such as occur in poison-oak or poison-ivy1 and botanists agree to call it ,rhus vernix4 ,the area in the ,eastern ,states where it is likely to be found is chiefly eastward from eastern ,minnesota1 northeastern ,illinois1 ,indiana1 central ,kentucky and ,tennessee1 and southeastern ,texas1 as shown on the shaded area of the map1 figure #bj4 ,this shrub is usually associated with swamps and bogs1 and the most typical growth occurs along the margin of an area of wet acid soil4 ,figure #ba4--,small branch of poison sumac with six compound leaves4 ,figure #bb4--;,fruit of poison sumac1 one-third natural size4 ,these fruits somewhat resemble those of poison-ivy4 ,they are always on drooping slender stems attached at the side of the small branches and are never terminal as in the species of sumac that are not poisonous4 ,the plants range in height from #e or #f feet to small trees that may attain a height of #be feet4 ,the poison sumac shrub shown in figure #ai is growing on the edge of a swamp and is quite typical of the general appearance of the larger shrubs1 which approach a treelike form4 ,as a rule the shrubs do not have a symmetrical upright treelike appearance4 ,they are more or less inclined to lean and have branched stems with about the same diameter from the ground level to the middle height of the shrub4 ,occasional isolated plants are found outside of swampy regions4 ,apparently these plants are started from seed distributed by birds4 ,the plants in dry soil usually do not become more than a few feet tall4 ,they are likely to cause poisoning to unsuspecting individuals1 as single isolated plants are not readily recognized1 especially out of their usual region4 ,the leaves of the poison sumac are divided into #g to #ac leaflets1 arranged in pairs with a single leaflet at the end of the midrib 7fig4 #ba74 ,figure #bc4--;,a1 ,smooth sumac and dwarf sumac growing in a mixed stand4 ,these plants are not poisonous4 ,b1 ,terminal fruiting spike of smooth sumac1 about one-seventh natural size4 ,this form of terminal fruiting spike is typical of all the species of sumac that are not poisonous4 ,the leaflets are an elongated oval shape without teeth or serrations on the margins4 ,they are #c to #d inches long and #a to #b inches wide1 with a smooth velvetlike texture and bright orange color when they first appear in spring4 ,later they become dark green and glossy on the upper surface and pale green on the lower and have scarlet midribs4 ,early in fall they turn to a brilliant red-orange or russet shade4 ,the small yellowish-green flowers are borne in clusters in slender stems arising from the axis of leaves along the smaller branches4 ,the slender clusters of flowers have much the general appearance of the poison-ivy flower1 but hang in much longer clusters4 ,the flowers mature into ivory-white or green-colored fruits resembling those of poison-oak or poison-ivy1 except that they are usually less compact and hang in loose clusters that may be #aj to #ab inches in length 7fig4 #bb74 ,,confusion ,,of ,,poisonous ,,and ,,harmless ,,sumacs ,because of the same general appearance of several common species of sumac and the poison sumac1 considerable confusion has occurred as to which one is poisonous4 ,throughout most of the range where poison sumac grows1 three other species are the only ones that are likely to be confused4 ,these are the smooth sumac 7,rhus glabra71 staghorn sumac 7,r4 typhina71 and dwarf sumac 7,r4 copallina74 ,all the nonpoisonous species have red fruits that together form a distinctive terminal seed head1 as shown in figure #bc4 ,these are easily distinguished from the slender hanging clusters of white fruit of the poison sumac1 as shown in figure #bb4 ,sometimes more than one species of the harmless sumac grow together1 as shown in figure #bc1 ,a4 ,when seed heads or flower heads occur on the plants it is easy to distinguish the poisonous from the harmless plants2 however1 in many clumps of either kind1 flowers or fruit may not develop4 ,fortunately1 the leaves have some rather distinct characteristics1 which can be easily observed4 ,figure #bd shows leaves of the three harmless species as compared with poison sumac4 ,the leaves of the smooth sumac 7fig4 #bd1 ,a7 and of the staghorn sumac 7fig4 #bd1 ,b7 have many leaflets1 which are slender lance-shaped with a toothed margin4 ,in these species there are usually more than #ac leaflets4 ,the leaves of the dwarf sumac 7fig4 #bd1 ,c7 and the poison sumac 7fig4 #bd1 ,d7 have fewer leaflets1 and these are more oval-shaped1 with smooth or even margins4 ,the dwarf sumac1 however1 may be readily distinguished from the poisonous sumac by the winged midrib of the leaf 7fig4 #bd1 ,e74 ,there is considerable variation in the size of the wing margin along the midrib1 which in some cases may be reduced almost to a line between the leaflets4 ,the winged midrib is more prominent near the terminal leaflet and can always be detected4 ,the midrib of the poison sumac is never winged4 ,a little study of the fruit and the leaf characteristics of the poisonous and harmless species will make it possible to avoid the poisonous one and utilize the other1 which has considerable value as an ornamental plant1 as a source of commercial tannin1 and for controlling erosion on waste hillsides4 ,figure #bd4--,leaves of species of sumac that are often confused3 ,a1 ,smooth sumac2 ,b1 staghorn sumac2 ,c1 dwarf sumac2 ,d1 poison sumac2 ,e1 enlarged portion of dwarf sumac leaf from ,c1 showing the wing margin of the midrib4 ,poison sumac does not have the winged midrib4 ,,introduced ,,poisonous ,,sumac ,,and ,,related ,,species ,the small ,japanese lacquer-tree1 although uncommon in the ,united ,states1 is an introduced species of sumac 7,rhus verniciflua7 that is quite similar to the native poison sumac4 ,it is native to ,japan and ,china and is the source of ,japanese black lacquer4 ,cases of poisoning hare been traced to contact with lacquered articles4 ,because of its poisonous properties1 this tree should never be planted4 ,a native shrub or small tree called poison-wood1 doctor gum1 or coral sumac is commonly found in the pinelands and hummocks of extreme southern ,florida1 the ,keys1 and the ,west ,indies4 ,it is much like the poison sumac and closely related to it4 ,most botanists name it ,metopium toxiferum1 although previously it was named ,rhus metopium1 and sometimes metopium is used as its common name4 ,the small tree1 or shrub1 has the same general appearance as poison sumac4 ,the leaves have the same general appearance1 except that there are usually only three to seven leaflets1 which are more rounded4 ,the fruits are borne in clusters in the same manner as those of poison sumac 7fig4 #bb71 but individual fruits are two or three times as large and orange-colored4 ,all parts of the plant are exceedingly poisonous to the touch and cause the same kind of skin irritation as poison-ivy or poison sumac4 ,,poisoning ,through experience1 many people know that they are susceptible to poisoning by poison-ivy1 poison-oak1 or poison sumac1 while some others either have escaped contamination or have a certain degree of immunity4 ,the extent of immunity appears only relative1 and absolute immunity to the toxic principle apparently does not exist4 ,persons who have shown a degree of immunity upon repeated contact with the plants may develop poisoning on subsequent exposure4 ,the skin irritant of poison-ivy1 poison-oak1 and poison sumac is the same toxic agent4 ,it is a nonvolatile phenolic substance called urushiol and is found in all parts of the plant1 including roots and fruit4 ,it occurs in great abundance in the plant sap4 ,the danger of poisoning is greatest in spring and summer1 when the sap is abundant1 and least late in fall or in winter4 ,poisoning is usually caused by contact with some part of the plant4 ,a very small quantity of the poisonous substance is capable of producing severe inflammation of the skin and can easily be transferred from one object to another4 ,clothing may become contaminated and is often a source of such prolonged infection that it is likely to be judged as a case of poisoning difficult to cure4 ,dogs and cats frequently touch the plants and transmit the poison to unsuspecting persons4 ,the poison may remain on the fur of animals for a considerable period after they have walked or run through poison-ivy plants4 ,smoke from burning plants will carry the toxin and has been reported to cause severe cases of poisoning4 ,cases of poisoning of children from eating the fruit have been reported4 ,a local belief that eating a few leaves of these plants will develop immunity in the individual is unfounded4 ,it never should be attempted4 ,no part of the plant should ever be taken internally1 as it is a violent irritant and poisonous to man4 ,cattle1 horses1 sheep1 hogs1 and other livestock apparently do not suffer from skin irritation caused by these plants1 although they have been observed to graze upon the foliage occasionally4 ,bees collect honey from the flowers1 though no reports are on record of any ill effects from the use of the honey4 ,the time between contamination of the skin and the first symptoms varies greatly with individuals and probably with conditions4 ,the first symptoms of itching or burning sensation may develop in a few hours or after #e days or even more4 ,the delay in development of symptoms is often confusing in attempting to determine the time or location when contamination occurred4 ,the itching sensation and subsequent inflammation1 which usually develops into water blisters under the skin1 may continue for several days from a single contamination4 ,persistence of symptoms over a long period is likely to be due to new contacts with plants or with previously contaminated clothing or animals4 ,severe infection may produce more serious symptoms1 which result in much pain through abscesses1 enlarged glands1 fever1 or complicated constitutional malfunction4 ,secondary infections are always a possibility in any break in the skin1 such as is produced by breaking vesicles that have formed as large water blisters4 ,,precautions ,,against ,,poisoning ,the most effective way to prevent poisoning from the plants is to avoid contact with them4 ,if it is necessary to work among them1 some measure of prevention can be gained by wearing protective clothing1 but it is necessary to remember that the active poisonous principle can easily be transferred4 ,some protection also may be obtained in advance by the use of protective creams or lotions4 ,they prevent the poison from touching the skin1 or make the active principle easily removed1 or neutralize it to a certain degree4 ,various formulas containing ferric chloride and glycerin have been used more or less effectively as a preventive measure1 although there may be some danger of pigmentation of the skin from the ferric chloride4 ,a common formula is ferric chloride1 #e parts2 glycerin1 #be parts2 alcohol1 #be parts2 water4 #ej parts4 ,a lotion of this formula applied to the exposed skin prior to contact with poisonous plants gives effective protection for many people4 ,it is especially effective if followed by thorough washing with soap and water4 ,such washing1 even if no protective lotion has been used1 is often effective in preventing poisoning4 ,proper precaution should be taken by repeated lathering with a strong alkali soap1 followed by thorough rinsing and repeating the process several times4 ,the water should be frequently changed1 and a shower or flowing water bath is preferable4 ,the soap probably only emulsifies the active principle1 and thorough rinsing is necessary to avoid spreading the poison to other parts of the body4 ,the ,united ,states ,public ,health ,service reports successful chemical protection against ivy poisoning by use of an oxidizing agent--sodium perborate prepared and used fresh as an ointment4 ,following is a formula given for the ointment3 ,cetyl alcohol1 #ce4a percent2 stearyl alcohol1 #e4c2 ceresin1 #c4e2 castor oil4 #bj4h2 mineral oil1 #ba4i2 ,duponol ,,wa pure1 #a4g2 sodium perborate4 #aj4j2 and boric acid1 #a4g percent4 ,a more recent less oily formula recommended for both mechanical and chemical protection is given as follows3 ,shellac1 #ac parts2 isopropanol1 #ca2 linseed oil1 #d2 titanium oxide1 #ab2 sodium perborate1 #ac2 talcum1 #bj2 and carbitol1 #c parts4 ,sometimes cottonseed oil1 olive oil1 or petrolatum is applied as a protective ointment when contamination is anticipated4 ,later the oil must be completely removed by repeated washing4 ,clothing1 wearing apparel1 and tools that have been contaminated are often difficult to handle without further danger of poisoning4 ,some who are more or less immune to poisoning often contaminate others by carelessness4 ,contamination on automobile door handles or on a steering wheel after a trip to the woods often causes prolonged cases of poisoning of persons who have not been near the plants4 ,one of the most effective ways for decontaminating articles is by thorough washing through several changes of strong soap and water4 ,contaminated clothing should not be worn again until thoroughly washed4 ,it should not be washed with other clothes1 and care should be taken to rinse thoroughly any implements used in washing4 ,dogs and cats can be decontaminated in the same manner2 precaution should be taken1 however1 to avoid being poisoned in doing the washing4 ,it is likely that most dry cleaning processes will remove any contaminant2 but there is always danger that clothing sent to commercial cleaners may cause poisoning to unsuspecting employees4 ,certain prophylactic inoculations for the prevention of ivy poisoning have been developed and used with limited success2 such treatment1 however1 should be administered by a physician only4 ,the theory that eating a few leaves of these poisonous plants will confer immunity is without foundation2 it should not be attempted even as an experiment1 because very serious poisoning is likely to result4 ,,treatment ,,for ,,poisoning#a #a ,for a fuller description of treatments for poisoning see3 ,united ,states ,public ,health ,service1 ivy and sumac poisoning4 ,pub4 ,health ,rpts4 ,sup4 #afa 7rev471 #h pp41 #aidc4 ,for sale by the ,superintendent of ,documents1 ,government ,printing ,office1 ,washington #be1 ,d4 ,c4 ,price1 #aj cents4 ,there seems to be no absolute quick cure for ivy poisoning for all individuals1 even though many studies have been made to devise effective remedies4 ,remedies may be helpful in removing the poisonous principle or rendering it inactive and for giving some relief from the irritation4 ,mild poisoning usually subsides within a few days1 but if the inflammation is severe or extensive a physician should be consulted4 ,self-treatment also has other dangers1 as the symptoms of ivy poisoning may be confused with those of other conditions and harm may be done by improper treatment4 ,in all cases the safest procedure is to consult a physician4 ,some tried remedies are effective on certain individuals and ineffective on others4 ,sometimes a person will find one remedy effective and later1 to his surprise1 get very little relief from it4 ,a large number of patent medicine remedies of doubtful value are commonly offered for sale4 ,the following are more or less standard measures that have been advocated by different individuals and found helpful in certain cases4 ,the ,united ,states ,public ,health ,service recommends a #aj percent alcoholic solution of tannic acid applied as a lotion4 ,it is stated that in using it the tops of the blisters should be rubbed off with sterile gauze saturated with the solution and that any large blisters should be opened with a sterile instrument4 ,the treatment should be repeated three or four times at #f-;hour intervals4 ,a modified form of this treatment recommends vigorous rubbing of the lesions with alcohol-soaked gauze to remove the tops of blisters1 followed by application of a #aj percent aqueous solution of tannic acid as a lotion4 ,any treatment involving opening of blisters and the application of alcohol is severe1 and many cases requiring such treatment should be handled by physicians4 ,one of the oldest well-established remedies is a fresh solution of one #e-;grain tablet of potassium permanganate dissolved in #a quart of water2 concentrations as much as #e percent1 however1 have been used4 ,the potassium permanganate is apparently active in neutralizing any poison that may remain on the surface of the skin and it has some therapeutic properties4 ,this solution may be applied freely to the irritated or contaminated skin1 but the skin should be rinsed with water a few minutes after the stronger solutions are used4 ,applications should be repeated every hour or two4 ,the brown stain it causes on the skin will in time wear off1 or it may be removed with lemon juice4 ,it more or less permanently stains clothing4 ,ferric chloride in combination with several other substances has been used effectively by many people4 ,one of the most common formulas is that given under the discussion of precautions against poisoning 7p4 #bb74 ,to this formula #a to #c percent of phenol is frequently added to reduce the itching2 however1 not more than #a percent of phenol should ever be used without the advice of a physician1 on account of the danger of systemic absorption and poisoning4 ,the solution should be freely applied to the irritated or contaminated skin every hour or two4 ,some instances of persistence of the brown discoloration of the skin have been reported4 ,for this reason its use is limited1 but for most individuals the discoloration completely disappears after a few days4 ,stain on clothing is usually permanent4 ,photographer's hypo solution has been used with good results in many cases4 ,this is a #aj-percent solution of sodium thiosulfate in water4 ,the irritated or contaminated skin should be bathed in it every hour or two4 ,it does not stain skin or clothing4 ,a calamine lotion with the addition of about #b percent of phenol is often used and in many cases is effective4 ,frequent applications are necessary4 ,for some people it is effective in relieving the itching4 ,the pink stain is not permanent4 ,it is better to leave inflamed areas exposed to the air rather than cover them with dressings4 ,if poisoning is so severe that dressings appear necessary1 a physician should be consulted before any home remedies are applied4 ,,eradication ,,of ,,plants ,poison-ivy#b can be killed either by mechanical means1 such as digging1 or by applying chemical herbicides4 ,the best modern herbicides are so deadly to plants that a single treatment kills all the leaves and #ij percent or more of the roots4 ,this is the easiest and least dangerous way to destroy these poisonous pests4 ,there are places1 however1 where chemicals cannot be used1 as in hedges and shrubbery where the poison-ivy is closely mixed with the valuable plants4 ,in such situations1 hand-pulling is the only satisfactory method4 ,at times also chemicals and spraying equipment are not available1 and then the mattock1 scythe1 or plow must be resorted to4 ,even with these simple tools some timing and handling methods are better than others4 #b ,for brevity1 the single designation poison-ivy is used under this heading to apply equally to all poison-ivies and to poison sumac4 ,,chemical ,,weed ,,killers ,by using care poison-ivy can be destroyed with chemicals without danger of poisoning to the operator4 ,except in very heavy growth1 one may stand at a distance from the plants and apply the herbicide without touching the leaves4 ,most chemicals are applied as a spray solution1 and many sprayers can be equipped with extension nozzles #b feet or more in length4 ,the greatest danger of ivy poisoning occurs from careless handling of gloves1 shoes1 and clothing after finishing the work4 ,garments should be worn that can either be destroyed after use or washed thoroughly in hot soda solution and soapsuds4 ,the chemicals thus far found most satisfactory on poison-ivy are1 in approximate order of effectiveness1 ammonium sulfamate1 #b1d-;,d 7#b1d-;dichlorophenoxyacetic acid71 ammonium thiocyanate1 borax1 carbon disulfide1 coal-tar creosote oil1 fuel oil and similar petroleum distillates1 sodium chlorate1 and sodium arsenite4 ,less effective chemicals include common salt1 kerosene1 gasoline1 calcium cyanamide1 ammonium sulfate1 and iron sulfate4 ,chemicals other than borax are best applied as a spray to the foliage4 ,borax is scattered dry on the soil around the plants4 ,any field or garden spray machine or even a sprinkling can is useful for applying the liquids1 but a common knapsack sprayer holding about #b gallons is convenient and does not waste the solution1 application should be as a fine spray under moderate pressure rather than a driving mist1 since the object is to wet the leaves of the poison-ivy and avoid wetting the leaves of desirable plants4 ,most chemicals used on poison-ivy are injurious to the foliage of all kinds of plants and must be applied with caution if the surrounding vegetation is valuable4 ,during the early part of the growing season the leaves of the poisonous plants usually tend to stand conspicuously apart from those of adjacent plants and can be treated separately if sprayed with care4 ,later the leaves become intermingled and injury to adjacent species is unavoidable4 ,chemicals other than oil are not injurious to the thick bark of an old tree1 and poison-ivy clinging to the trunk can be safely sprayed with them4 ,chemical sprays can be used at any time when poison-ivy is in full leaf1 ,june and ,july being perhaps the best months4 ,ordinarily treatments should begin not later than ,august #ae1 as poison-ivy then begins to go dormant and sprays are ineffective4 ,best results are obtained both with sprays and with dry chemicals when the soil is moist but not wet at time of treatment4 ,borax can well be applied just before a rain1 but sprayed chemicals are likely to be washed off if rain falls within #bd hours4 ,one gallon of spray solution is sufficient to cover all the leaves on #a square rod 7#bgb square feet7 of dense poison-ivy1 or #b to #d square rods of a scattered stand4 ,sprays give best results when applied in early morning or late afternoon when the air is cool and moist4 ,spraying in the middle of a dry1 hot day is likely to be disappointing unless the plants are in deep shade4 ,no method of chemical eradication can be depended upon to kill all the plants in a stand of poison-ivy with one application4 ,three to four light retreatments made as soon as the new leaves are fully expanded are always necessary 7#a7 to destroy plants missed the first time1 7#b7 to treat new growth from the old roots1 and 7#c7 to destroy seedlings4 ,at least three and sometimes four treatments at intervals of #b to #h weeks are necessary before all plants are dead4 ,these followup treatments do not require much time or material1 but neglect of them may easily lead to serious reinfestation4 ,poison-ivy has an annoying habit of playing possum4 ,plants believed dead sometimes revive after many months4 ,thus an area under treatment must be watched closely for at least a year if complete eradication is to be assured4 ,dead foliage and steins remaining after the plants have been killed with chemicals are only slightly poisonous1 but to avoid difficulty the dead stems should be cut off and burned4 ,ammonium sulfamate4--,this chemical1 under a proprietory name1 has come on the market recently as a weed killer and has proved especially useful against poison-ivy4 ,ammonium sulfamate is not dangerous to use under ordinary conditions1 is not harmful to the soil1 and is not flammable4 ,it is slowly corrosive to metals1 and spray equipment should be washed thoroughly with a solution of lime or soda immediately after use4 ,like salt1 ammonium sulfamate absorbs moisture from the air and must be stored in a dry place4 ,ammonium sulfamate is dissolved in water at the rate of #ab ounces per gallon and sprayed on the leaves until they are wet but not dripping4 ,the foliage begins to wilt within #ba hours1 but the action is slow1 and a week or more may elapse before the leaves die4 ,some new growth may be expected after #d to #h weeks1 and this should be sprayed as soon as the new leaves are fully expanded4 ,two or occasionally three such retreatments are needed before the kill is complete4 #b1d-;,d 7#b1d-;dichlorophenoxyacetic acid74--,this chemical under the abbreviated name #b1d-;,d1 or ,,dcp1 is a recent addition to the list of effective weed killers and may become an important weapon for use against poison-ivy4 ,it should not be confused with ,,ddt or ,,dd1 two other new agricultural chemicals1 the first an insecticide and the second used as a soil fumigant4 ,under wartime restrictions the use of #b1d-;,d was very limited1 but its prospective value is so great that those interested in the control of poison-ivy should be informed about it4 ,the chemical #b1d-;,d is one of the so-called plant hormones1 or growth regulators4 ,in minute quantities it stimulates some of the plant functions1 but in slightly larger dosage it is toxic4 ,a solution consisting of one-seventh ounce in #a gallon of water sprayed on poison-ivy foliage kills all leaves hit and may kill the roots4 ,in the concentration used in weed killing #b1d-;,d is not believed to be harmful to animal life1 but until this point can be thoroughly clarified the chemical should be used with reasonable caution to avoid poisoning4 #b1d-;,d is not flammable and is not corrosive to spray machinery4 ,if the sprayer is used also for insecticides and fungicides it must be washed very thoroughly to remove the slightest trace of the #b1d-;,d4 ,this is very difficult1 however2 it is safer to use another sprayer4 ,to make a spray solution #b1d-;,d must be combined with other chemicals1 as it is not soluble in water4 ,a number of substances1 including polyethelene glycols and naphthenic soaps1 have been used for this purpose1 but the best solvent has not yet been determined4 ,commercial weed killers containing #b1d-;,d are of varying composition4 ,ammonium thiocyanate4--,this byproduct of the coal-gas industry is one of the newer herbicides4 ,the crude commercial chemical is a pink or reddish salt1 very soluble in water4 ,it does not keep well1 tends to disintegrate into a red1 sludgy mass1 and is difficult and disagreeable to handle4 ,a purer form in clean white crystals is available and is well worth the slight extra cost4 ,in either form ammonium thiocyanate is injurious to the skin and to leather articles1 and in time it corrodes metals4 ,the spray solution is made by dissolving #a to #a pounds of ammonium thiocyanate in #a gallon of water4 ,most annual1 plants and some perennials are killed by a single application of ammonium thiocyanate4 ,poison-ivy usually requires three or four treatments4 ,ammonium thiocyanate has a high content of nitrogen1 much of which remains in the soil and eventually becomes a fertilizer4 ,thus an area treated with this chemical is likely to produce a profuse growth of annual weeds a month or two after treatment4 ,borax4--,common borax scattered on the soil is deadly to the roots of many plants4 ,spread dry at the rate of #aj to #ae pounds per square rod1 it kills poison-ivy slowly over a period of #f to #h weeks4 ,a second somewhat lighter treatment #c to #e months later is usually necessary to kill all plants completely4 ,borax is easy to handle1 nonpoisonous1 and nonflammable1 readily obtainable1 and not expensive4 ,it is one of the best chemicals to use around stone walls1 rocky ledges1 fences1 and other inaccessible places4 ,plants differ greatly in their resistance to borax4 ,some species1 as ,virginia creeper and deep-rooted trees1 do not seem to be injured1 but others1 notably dogwood1 are very sensitive to it4 ,until more complete information is available as to the effect of borax on other plants1 it should be employed on poison-ivy only where possible damage to surrounding vegetation is not objectionable4 ,carbon disulfide4--,the fumes of this pungent1 volatile liquid are very poisonous to plants1 and the chemical is widely used in the ,west to kill deep-rooted perennial weeds4 ,when poison-oak1 particularly1 is growing in a mixture with wild morning-glory 7bind-weed7 or similar noxious weeds1 both plants may often be killed at one operation by treating the soil with carbon disulfide4 ,holes ordinarily #f inches deep and #ah inches apart in all directions are punched in the soil with a #a-;inch iron bar1 and #b ounces of carbon disulfide are poured in each hole4 ,the openings are closed immediately with a wooden club4 ,this dosage equals #bj pounds of the chemical per square rod4 ,carbon disulfide is likely to be less effective on shallow-rooted than on deep-rooted plants and is therefore of limited value against poison-ivy1 which is surface-rooted4 ,carbon disulfide is poisonous1 and as it is also highly flammable it should be handled as carefully as gasoline4 ,coal-tar creosote oil4--,in the fractional distillation of coal1 many oils and oillike substances are obtained1 some of which are very toxic to plants4 ,the most common and usually the cheapest is the creosote used for wood preservation4 ,this substance has great penetrating power and is an excellent herbicide on woody plants like poison-ivy4 ,ordinarily creosote oil is too expensive to use alone and is therefore mixed with some kind of petroleum oil4 ,a mixture of #ge percent fuel oil and #be percent creosote oil is almost as effective as straight creosote and is made at one-third the cost4 ,two applications of this mixture at an interval of about #f weeks usually kill a high percentage of poison-ivy4 ,creosote is not selective and kills all plants alike4 ,fuel oil 7,diesel and similar oils74--,crude petroleum is refined into many kinds of oil1 and those corresponding to fuel oil4 ,diesel oil1 stovetop oil1 and orchard-heating oil are more injurious to plants than crude oil itself or the higher distillates1 such as gasoline and kerosene4 ,fuel oils are widely used for destroying vegetation1 particularly by highway departments in ,states having oil resources4 ,when sprayed on poison-ivy1 fuel oil brings about a slow but fairly sure death of the plants4 ,two or three applications may be necessary before the roots are killed4 ,fuel oil1 like creosote1 must be used with care around valuable trees and shrubs because it penetrates the bark and kills or injures all species4 ,as used for poison-ivy spraying there is no injury to the soil4 ,the oil-soaked vegetation is flammable4 ,sodium chlorate4--,sodium chlorate is the standard herbicide for killing deep-rooted perennial weeds like bindweed1 but when used as a spray1 it is a dangerous fire hazard1 and when applied dry1 it sterilizes the soil for #b to #d years4 ,where sterilization of the soil is desirable or not objectionable1 one application of the dry chemical1 evenly at the rate of #c to #d pounds per square rod1 is sufficient for a complete kill4 ,if used as a foliage spray on poison-ivy1 the chemical is dissolved in water at the rate of #h to #ab ounces per gallon4 ,the leaves are killed within a few hours1 but the plants are likely to make a strong new growth and may require as many as six treatments before they cease to produce new leaves4 ,sodium chlorate mixed with wood1 cloth1 or other organic materials is highly combustible and easily ignited4 ,shoes and clothing on which chlorate solution has been allowed to dry are especially dangerous1 for they will ignite and burn with explosive fury4 ,contaminated clothing should be kept wet until thoroughly washed in a large volume of water4 ,chlorate should be stored only in original metal containers1 as any admixture of chlorate1 wet or dry1 with straw1 wood1 dust1 cloth1 or leather has properties similar to those of gunpowder or matches4 ,sodium arsenite4--,sodium arsenite is one of the most powerful plant poisons known and is widely used for sterilizing soil on railroads1 roadways1 and other places where no vegetation of any kind is desired4 ,it is relatively inexpensive4 ,in normal times sodium arsenite is obtainable in both powder and liquid form4 ,in weak solution 7#d to #f ounces per gallon of water7 the chemical can be used as a spray to destroy poison-ivy4 ,like sodium chlorate spray1 it kills the leaves but not the roots1 and five or six treatments may be required4 ,the solution kills the leaves of all plants impartially and will also kill the young tender bark of shrubs and trees4 ,this may be either an advantage or a disadvantage1 depending upon circumstances4 ,all compounds containing arsenic are deadly poisons if taken internally4 ,arsenical sprays and chemicals should not be used where there is any possibility that materials sprayed with them will be eaten by animals or man4 ,in some communities special permission must be obtained before arsenical weed killers may be used4 ,,eradication ,,by ,,mechanical ,,means ,poison-ivy can be grubbed out by hand quite readily early in spring and late in fall4 ,when the ground is soft after rains the roots come out in long pieces4 ,grubbing when the soil is dry and hard is almost futile1 since the roots break off in the ground1 leaving large pieces that later sprout vigorously4 ,eradication by grubbing is permanent if well done4 ,because of his close contact with the plants1 the person doing the grubbing should have a high degree of immunity to ivy-poisoning4 ,many people are not so immune as they believe1 and it is common sense to wear leather gloves with gauntlets and a shirt with long sleeves4 ,if care is taken to prevent the poison-ivy from touching the face1 and if the clothes1 including the gloves1 are burned or thoroughly washed after use1 severe poisoning may be avoided4 ,poison-ivy vines climbing on trees should be severed at the base and as much of the vine as possible pulled away from the tree4 ,often the roots of the tree and weed are so intertwined that grubbing is impossible without injury to the tree4 ,close mowing of the poison-ivy shoots at frequent intervals is the only remedy4 ,roots and stems removed in grubbing should be burned or otherwise destroyed1 since the dry material is almost as poisonous as the fresh4 ,care must be taken to keep out of the smoke4 ,old plants of poison-ivy produce an abundance of seeds1 and these are freely disseminated1 especially by birds4 ,a poison-ivy seedling #b months old usually has a root that one mowing will not kill4 ,seedling plants at the end of the first year have well-established underground runners that only grubbing or chemicals will kill4 ,seedlings are a constant threat as long as old poison-ivy is in the neighborhood4 ,plowing is of little value in combating poison-ivy unless followed by persistent stirring with a cultivator or harrow1 to keep all roots loosened from the soil4 ,otherwise plowing merely propagates the weed4 ,mowing with a scythe or sickle is a common method of attacking poison-ivy1 but it has little effect on the roots unless frequently repeated4 ,the number of cuttings required to kill depends upon the age of the plants and the size of the roots1 but is seldom less than four4 ,new shoots should be cut as soon as the first leaf on each stem is full size4 ,cutting either earlier or later delays eradication4 ,weed burners are implements resembling oversize blowtorches4 ,two types are manufactured1 one producing a short1 hot1 blue flame and the other a long smoky-yellow flame4 ,both are useful for destroying foliage4 ,neither is likely to kill perennial plants like poison-ivy at one operation1 even though the flame is held on the weeds for a minute or more until leaves and stems are completely incinerated4 ,the roots are not injured by this1 and new leafy shoots soon develop4 ,a better plan is to sear the plants by passing the flame slowly over the vines just long enough to sear or wilt the leaves1 but not long enough to burn them4 ,the roots appear to be injured more by searing than completely burning the leaves1 and the operation is quicker and cheaper4 ,three to four searings when the leaves reach full size usually kill the roots4 ,u4 ,s4 ,government ,printing ,office3 #aide--febeab ,for sale by the ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office1 ,washington #be1 ,d4 ,c4 99 99 99 99 99 ,transcriber ,notes ,all illustrations were moved so as to not split paragraphs4