Wild Garlic, Its Characteristics and Control."

Lé / jinpifi á- AMÑl ilV3 USDA policy does not permit discrimination because of age, race, color, national origin, sex, or religion. Any person who believes he or she has been discrîminated against in any USDA-related activity should write immediately to the Secretary of Agriculture, Washington, D.C. 20250

11 This publication reports research involving pesticides. It does not contain recommendations for their use, nor does it imply that the uses discussed here have been registered. All uses of pesticides must be registered by appropriate State and/or Federal agencies before they can be recommended. CAUTION: Pesticides can be injurious to hu- mans, domestic anipials, beneficial insects, desirable plants, and fish or other wildlife—if they are not handled or applied properly. Use all pesticides selectively and carefully. Follow recommended practices for the disposal of surplus pesticides and pesticide containers.

This bulletin supersedes Agriculture Handbook 298, "Wild Garlic, Its Characteristics and Control."

Washington, P.C. Issued July 1976 For sale by the Superintendent of Documents, U.S. Government Printing Office Price 40 cents; 25% discount allowed on orders of 100 or more to one address Washington, D.C. 20402 Stock No. 001-000-03526-6 There is a minimum charge of $1.00 for each mail order iii CONTENTS Page Origin and distribution 1 Plants that resemble wild garlic 2 Description and growth habit 3 Classification 3 Structure of the wild garlic plant 3 Plant types 4 Bulb types 5 Reproductive cycles 8 Wild garlic: a pest 12 Pest in small grains 12 Pest of pastures and hay fields 13 Pest around homes and in noncrop areas 14 Control and eradication 14 Cultural control 14 Chemical control 16 Chemical control in turf and pastures 18 Chemical control in small grain fields 19 Chemical control in waste areas 19 Precautions 19 Parasites and diseases 20 Literature cited ^ 21

IV WILD GARLIC Life Cycle and Contror

Elroy J. Peters, research agronomist, North Central Region, Agricultural Research Service, U.S. Department of Agriculture, Columbia, Mo., and J. F. Stritzke, associate professor, Oklahoma State University, Stillwater, Okla.

Wild garlic (Allium vineale L.) products. Other common names is a troublesome weed in the that have been used for Allium United States. Significant losses vineale L. are field garlic, meadow result from the "onion" odor and garlic, garlic, onion, crow garlic, ñavor that wild garlic gives to wild onion, and vineyard garlic milk, small grains, and meat (3,27y

ORIGIN AND DISTRIBUTION

The geographical origin of wild Canary Islands (12). Wild garlic garlic is difficult to determine. It has spread from Europe to Aus- probably originated in the area tralia (2), New Zealand (38), and of the Mediterranean Sea (18). the United States. It is particu- Wild garlic is found in many larly troublesome in Sweden, areas of the world. It has spread England, and the United States throughout western and central (13,20,27,28). Europe and is found as far north Wild garlic was probably in- as southern Norway, Sweden, and troduced into the United States Finland and east to the Dneiper, from France in the 17th or early Crimea, and Transcaucasian re- part of the 18th century (3,15). gions of the USSR (13,31). After being introduced into the It is^ rare in Austria ; is fairly United States, it became a serious common in Hungary, Italy, Spain, weed problem. Pipal cited a re- and Portugal (12) ; and has been port showing that as early as reported in North Africa and the 1754, in Philadelphia, an infes- ^ Prepared in cooperation with Mis- souri Agricultural Experiment Station ^ Italic numbers in parentheses refer (Journal Series No. 7203). to Literature Cited, p. 21. tation of wild garlic in a wheat- New York, Ohio, and Michigan field was so heavy that one garlic (10). It is a serious pest on the head was present for every nine eastern seaboard and west to heads of wheat (28). Kansas and Oklahoma (30). Wild Wild garlic has continued to garlic has been mentioned as the spread and now infests a large cause of garlic-ñavored milk in part of the United States. It grows as far south as Georgia, Wyoming (6). Infestations also Mississippi, and Arkansas; and are present in western Oregon as far north as Massachusetts, and Washington.'

PLANTS THAT RESEMBLE WILD GARLIC

In the United States, wild garlic sometimes grows in associa- tion with such other bulb formers as Ornithogalum umbellatum L., Allium oleraceum L., A cernuum Roth, A. mutabile Michx., A. canadense L., Hemerocallis fulva L., and Zigadenus nuttallii Gray. The terms "wild garlic" and "wild onion" are often used in- terchangeable for many of the bulb formers. In the United PN-4408 States, the species most commonly Figure 1.—Cross sections of leaf blades found with wild garlic are wild of star-of-Bethlehem, wild onion, and onion (A. canadense L.) and star- wild garlic: A, leaf of star-of-Bethle- of-Bethlehem (Ornithogalum um- hem showing white striation at the center of the solid flat leaf; B, flat bellatum L.). solid leaf of wild onion; C, round, Wild garlic can be distinguished hollow leaf of wild garlic. from wild onion and star-of- Bethlehem by its striate, nearly round hollow leaves (fig. 1, C), coat of wild onion is fibrous which are attached at the lower matted. Star-of-Bethlehem does half of the plant. Wild onion and not have the "onion" odor of wild star-of-Bethlehem have their solid garlic or wild onion. flat leaves attached at the base The wild onion, like wild garlic, of the plant. Moreover, wild garlic begins growth in mid-August or has underground hardshell bulbs, early September and matures in which are absent on wild onion and star-of-Bethlehem. Also, the • Personal communication from Dr. old bulb coat of wild garlic is Marion Ownbey, Dept., of Botany, thin and membranous, but the Wash., State Univ. late May or early June. Wild showy white flowers appear, and onion grows 1 to 2 feet tall. It then tiie plants mature and dis- has flat leaves (ñg. 1, B), which appear before warm weather. arise from the base of the plant. Star-of-Bethlehem seldom grows Star-of-Bethlehem often is over 8 inches tall. It has flat planted as an ornamental and leaves, which have a white stripe then spreads to lawns, gardens, yards, and waste places. It begins down their center (fig. 1, A). The growth soon after the ground leaves arise from the base of the thaws in early spring. Small, plant.

DESCRIPTION AND GROWTH HABIT

Classification forma capsvliferum Koch, with a umbel consisting of flowers only. Wild garlic is a bulbous peren- Three forms of wild garlic nial monocot that has classically have been îdentifled in England, been included in the Liliaceae but their status as varieties has family. However, Hutchinson been questioned by Richens (SI). (H) includes Allium in the Transitions between forms are Amaryllidaceae family. He con- often noted, and they appear to siders the umbellate inflorescence be dependent upon Mendelian to be of greater taxonomic im- allelic genes (15). Most Allium portance for classification than species have 16 chromosomes, but the character of superior or in- Allium vineale L. has 32 chromo- ferior ovary, which is usually somes, a number that indicates used to distinguish Liliaceae from that A. vineale L. is tetraploid Amaryllidaceae. Other workers (15). Apogamy is a common oc- support his views (5,26), currence in A. vineale. Five varieties or forms of Iltis (15) also observed what Allium vineale L. have been de- he thought to be genetic differ- scribed in the United States ences in color of aerial bulblets. (15). These are (a) forma typi- cum Beck, with a loose umbel Seed from plants with purple bulblets produced plants with containing both aerial bulblets purple leaf sheaths and seed from and flowers; (b) forma compac- plants with green bulblets pro- tum Thuill, with a compact head duced plants with green leaf consisting only of aerial bulblets, which are greenish or whitish; sheaths. (c) forma fuscenscens Ascherson and Graebner, with a head con- Structure of the Wild taining reddish bulbils ; (d) forma Garlic Plant crintium Jacob, with bulbils on Wild garlic looks much like the head tipped with long, green, cultivated onion. Figure 2 shows capillary appendages; and (e) a clump of wild garlic as seen

3 The flowers have a greenish to purple perianth with lanceolate to elliptic segments. The segments are obtuse to acutish and about îtî'V:- T

PN-4409 Figure 2.—A typical clump of wild garlic in the spring, showing growth habit and plants of various sizes. The larger upright plants are scapigerous and the smaller plants are nonscapigerous.

in spring. The leaves, two-ranked, have sheathing bases. The leaf blades are circular in cross section and hollow. The outer layers of a bulb of a growing wild garlic plant are formed from the sheathing bases of the foliage leaves.

Plant Types Wild garlic consists of two plant types — scapigerous and nonscapigerous. The larger, scapigerous plant bears a scape, which PN-4410 produces aerial bulblets (ñg. 3) Figure 3.—Scapigerous garlic plant as and sometimes flowers (fig. 4). seen at maturity in June. Figure 4.—Umbels on scapes of wild garlic. The umbel on the left is a double umbel (single umbels are more common but plants may have as many as three or four) with aerial bulblets only. Umbel on the right contains bulblets and flowers (less common).

as long as the stamens {10). Bulb Types Seeds of the scapigerous plant Four types of bulbs can be are black, flat on one side, and found on wild garlic at the end about one-eighth inch long. of a season's growth in late The number of scapigerous spring. In naming bulb types, the plants varies in a wild garlic system of nomenclature suggested stand. Under conditions in the by Davis and Peters {7) will be British Isles, Richens observed used in this publication. that about 30 percent of the vi'ild garlic population consists of Aerial bulblets scapigerous plants in any one As many as 300 aerial bulblets season {31). The rest of the pop- (fig. 6, A) may be formed on the ulation -viSiS made up of non- scape of a scapigerous plant scapigerous plants (fig. 5), which (fig. 3). are shorter and less conspicuous The bulblets develop within a than the scapigerous plants. spathe (a large, dry, thin, mem- Nonscapigerous plants have branous bract) at the top of the slender foliage and fewer leaves scape. The spathe contains no and do not produce a scape at the green color and remains closed end of the growing season. until near maturity in late spring. Iltis (15) describes three forms of aerial bulblets found in Vir- ginia, each form appearing in a separate head. One form of bulblet is whitish or yellowish with pointed, greenish, or purple tips that are bent slightly to one side. The second form is dark purple without appendages. The third form of bulblet has green appendages that are 2 to 3 inches long. The appendages, or leaf blades, are usually fully developed within the spathe before it bursts. Barnes* showed that the formation and length of appendages could be altered by temperature. When wild garlic plants were grown continuously at 70° F under a 12-hr daylength, the outer protective leaf of the aerial bulblet developed a long append-

FN-4412 age that continued to grow and the aerial bulblet developed roots Figure 5.—The nonscapigerous plant a« seen at maturity in May. These and became an independent plant. plants usually mature about a month If the plants were grown con- earlier than the scapigerous plants. tinuously at 50° under a 12-hr daylength, no appendages developed. But when plants were exposed to temperatures of 50° or lower and then grown at 70°, short appendages developed, but Then the spathe bursts, exposing these dried up as the plant ma- aerial bulblets and flowers. tured. The aerial bulblet consists of a fleshy, cone-shaped scale containing a growing point at its Hardshell bulbs base. The fleshy scale is a blade- The second most numerous type less storage leaf. Surrounding the of bulb is the hardshell bulb storage leaf is a protective scale (ñg. 6, B). Larger than aerial consisting of two or three cell layers. The protective scale is a bladeless leaf in most cases, but * Barnes, Donald L. Effects of En- it may include a blade, which was vironment and a Growth Substance on Development of Wild Garlic {Allium referred to by Iltis (15) as an Vineale L.). (Ph.D. Dissertation, Uni- appendage. versity of Missouri. 1970.)

6 Figure 6.—The four bulb types of wild garlic: A, aerial bulblet; B, hardshell bulb; C, central bulb; and D, soft offset bulb. bulblets, hardshell bulbs have a The structure of a central bulb single bladeless storage leaf that is similar to other bulb types. contains a growing point at its However, it sometimes does not base. The storage leaf is sur- have an outer protective scale and rounded by a bladeless leaf that is surrounded only by the with- forms a hard protective shell. ered bases of foliage leaves. When Hardshell bulbs are formed un- the outer scale is present, it is derground in the axils of the prolonged into a sharp terminal outer leaves of scapigerous and point. nonscapigerous plants (fig. 7). The hardshell bulb is the only Soft offset bulb bulb type that is produced by the scapigerous and nonscapigerous The soft offset bulb (fig. 7, D) plants. is formed underground in the axil of the innermost leaf of the Central bulb scapigerous plant. It is similar in The central bulb (fig. 7, B) is structure to the other bulb types formed underground by non- and usually is the largest of the scapigerous plants and is con- four types. It is ovate in longi- spicuous at the end of a season's tudinal section and has a convex growth. It is formed around the abaxial face and a flat adaxial main axis of the plant. The cen- face, which form two distinct tral bulb, circular in cross sec- ridges where the faces meet (fig. tion (fig. 6, C), varies from the 6, D). The ridges tend to clasp small size of an aerial bulblet up the sides of the flattened scape to to that of a soft offset bulb. which they are attached. FN-4414 Figure 7.—(Left) Longitudinal section of the base of a mature nonscapigerous plant showing (A) the hardshell bulbs and (B) the central bulb. (Right) Longitudinal section of the base of a mature scapigerous plant showing the positions of (C) hardshell bulbs and (D) a soft offset bulb.

REPRODUCTIVE CYCLES

Figure 8 shows the reproduc- abundant viable seed (15,Si). In tive cycles of wild garlic. Virginia and Delaware, for ex- Each type of bulb is capable of ample, seed production is com- producing either a scapigerous or mon {1,15). When seeds are pro- a nonscapigerous plant. The non- duced, they usually are viable scapigerous plant produces one (13,15). Garlic seeds are pro- central bulb and sometimes one or duced in the spring and germinate two hardshell bulbs at maturity. the following fall. Seedlings evi- The scapigerous plant produces dently are nonscapigerous; they seed and aerial bulblets above develop only one small bulb dur- ground plus one soft offset bulb ing the first year (15). and one to six hardshell bulbs Wild garlic is usually spread below ground. by bulbs rather than by seeds. Production of seed is insignifi- Aerial bulblets are more numer- cant in most garlic habitats, ex- ous than other bulb types, and cept near the southern limits of therefore, are responsible for its range in the United States most of the dispersion of wild where wild garlic may produce garlic.

8 Seed

Nonscapigerous Plant

Scapigerous Plant

Nonscapigerous Scapigerous Plant Plant Figure 8.—Relationship between bulb types, seed, and plant types in the reproductive cycles of wild garlic. The bulb types will give rise to either a scapigerous or nonscapigerous plant. Seed will give rise to a nonscapigerous plant the first year and give rise to either type of plant later. Refer to figure 7 for location of the underground bulbs for each type of plant. 9 Aerial bulblets that complete vation in Missouri has shown that growth in spring (May and June) frequently two bulblets can be sprout the following fall. Plants found within the same covering developing from aerial bulblets leaf, giving the impression that may produce scapes (19), but only one bulblet is present. they usually produce nonscapi- Figure 10 shows the develop- gerous plants that develop only mental stage of a growing scapi- leaves above ground. gerous plant in April. The growth of the nonscapi- The first bulbs developed in the gerous plant is unique because it scapigerous plant are the hard- terminates a season's growth with shell bulbs, which form in the the formation of one central bulb axils of the outer foliage leaves. containing a stem apex and some- Growth of the scapigerous plant times two hardshell bulbs in the is terminated with the formation axils of the foliage leaves (fig. 7). of the spathe on the plant axis In Missouri, development of cen- and the formation of one soft tral bulbs first becomes apparent offset bulb in the axil of the in- in early winter and development nermost foliage leaf (fig. 10, B). of hardshell bulbs usually becomes apparent in February or March. Figure 9 shows a longitudinal section of the basal por- tion of a growing nonscapigerous plant examined in April. Plants developing from aerial bulblets may, in some instances, produce a scape, a soft offset bulb, and hardshell bulbs in one season. Freeman (11), in Kentucky, found that about 33 percent of the plants from aerial bulblets produced scape the first year. Iltis (15), in Virginia, and Pipal (28), in Indiana, have reported that plants growing from aerial bulblets develop secondary bulblets at the base of primary bulblets in the fall, and the secondary bulblets grow into separate plants during the winter. A development similar to this PN-4415 was described, but was shown to Figure 9.—Longitudinal section of the be growth from two bulblets lo- base of a nonscapigerous garlic plant on April 15 showing the origin of the cated close together within the central bulb (A) and the hardshell same covering leaf (IS). Obser- bulb (B).

10 During this after-ripening period from early June to late July, the root and leaf primordia elongate slowly. At the conclusion of the after-ripening period, primordia elongate rapidly. In hardshell bulbs, little or no elongation occurs during the after-ripening period until late August when about 20 to 35 percent of the hardshell bulbs break dormancy and sprout. Leaf and root growth in the remaining dormant hardshell bulbs essentially ceases, and these bulbs break dormacy slowly and some may remain dormant up to 6 years (35). Sprouting of hardshell bulbs starts in mid-August or early September and nearly ceases by October or November. Studies in Missouri showed essentially no sprouting after November. How- PN-4416 ever, many shoots of sprouted Figure 10.—Longitudinal section of the bulbs did not emerge from the base of a scapigerous garlic plant on soil until spring. Freeman and April 15 showing the origin of the scape (A), soft offset bulb (B), and Kavanaugh (12) and Mitchell hardshell bulbs (C). and Sherwood (25) reported that wild garlic was observed emerg- ing from the soil in March and April. Central bulbs and soft offset bulbs start sprouting in early fall. Freeman (11) found that about These bulbs usually produce large two-thirds of the plants produced plants, three-fourths of which from hardshell bulbs were non- produce scapes (11). scapigerous the first year. All types of wild garlic bulbs The mechanism that determines have a short after-ripening period whether a bulb produces a scapi- following scenesence of the parent gerous or a nonscapigerous plant plant (32). In aerial bulblets, is not known. Richens thought central bulbs and soft offset bulbs, plant type is determined in the anatomical changes occur during early development of the plant the after-ripening period which (31 ) and that it is associated with appear to be a maturation process food reserve in the bulb. Planting similar to that occurring in seeds of soft offset and central bulbs at with immature embryos (33). depths of 4 inches or more re-

11 duces the number of scapes creased the percentage of scape- formed from these bulbs (21 ). All producing plants to 52 percent. plants from bulbs planted 2 inches This indicates that food reserves deep produced scapes, but only are consumed in emergence and 76 percent of the plants from bulbs planted 4 inches deep pro- that plants growing from great duced scapes. Increasing the depths cannot replenish their food depth of planting to 8 inches de- reserves and produce scapes.

WILD GARLIC: A PEST

Wild garlic contains allyl Sul- Wheat is graded garlicy when fide that has a disagreeable odor two or more green aerial bulb- and imparts a garlicy flavor to lets, or an equivalent of dry or agricultural products tainted with partially dry bulblets, are present it. in 1,000 grams of wheat (37). Wild garlic is a poor competi- Aerial bulblets also have a tor, and therefore, generally does high moisture content and when not reduce crop yields, but it often present in wheat, their moisture persists under row-crop culture. adds to the problems of milling Because wild garlic is drought the wheat. hardy, cold hardy, and tolerant Because wheat kernels and to wet soils, it is found on poorly aerial bulblets are similar in size drained land along rivers and (fig. 11), the fresh bulblets can- creeks, as well as on hillsides not be removed from the wheat (28,31). Wild garlic grows in with conventional grain-cleaning many types of soil (17), but it is vequipment. best adapted to heavy soil (31). A garlicy odor remains in wheat even when the bulblets are Pest in Small Grains removed. However, when wheat contain- Wild garlic is a pest of fall- ing aerial bulblets is stored for planted crops and is especially 6 months, the bulblets generally troublesome in small grains, will be dry enough to remove which have a similar growing with a fanning mill (27). season. Aerial bulblets are present Artificial heat also has been when small grains ripen and often used with some success for dry- are harvested with the grain. ing bulblets harvested with wheat Harvesting bulblets with wheat (28). that is used for flour is particu- Aerial bulblets float when larly objectionable because the wheat containing them is im- bulblets taint the flour. Products mersed in water, but the wheat made from garlicy flour usually then has to be dried. Drying retain the garlicy flavor. makes the large-scale use of the

12 PN-4417 Figure i2.—Showing the similarity in size of A, grains of wheat, and B, aerial bulblets of wild garlic.

immersion technique of removal Pest of Pastures impractical (27). and Hay Fields Investigations have been made Losses from wild garlic proba- to determine the effects of storage bly are greatest in the dairy in- on germination of wheat contain- dustry. Milk from cows grazed on ing aerial bulblets (16). Germina- garlic-infested pastures develop tion of wheat is not adversely the garlicy flavors. Also, a small affected by 7 months of storage amount of garlic in the ration of and then most aerial bulblets are dairy cows taints the dairy prod- no longer viable In one test, ucts made from such milk. however, some aerial bulblets re- Arbuckle (i-) stated that garlic mained viable for about 2 years was the main cause of off-flavor (16). in milk in Maryland. Attempts to destroy the via- Many authorities believe that bility of aerial bulblets in wheat removing cattle from garlic-in- by rolling (crushing) also have fested pastures for 3 or 4 hours been made (16). One rolling did before milking reduces or elimi- not affect sprouting and two roll- nates the flavor in milk (^,6,27). ings only slightly reduced sprout- But Pipal (28) stated that off- ing of aerial bulblets. flavor persisted in milk for sev-

13 eral days after dairy cows were Populations of wild garlic build removed from garlic-infested pas- up in lawns, gardens, and waste tures. He also reported that cattle areas where they serve as sources grazed on wild garlic had garlic- of infestations to adjoining areas. flavored meat. In one case, the Wild garlic spreads from one garlic flavor persisted in the meat place to another mainly through of a cow that had been removed movement of bulblet - infested from a garlic-infested pasture 10 small grains, hay, straw, and days before slaughter. Because manure. But all types of bulbs of garlic infestations, many pas- can be spread in soil moved dur- tures cannot be used in fall or ing construction of buildings, spring when the garlic is growing. ponds, terraces and roads. Garlic infestations in lawns most often are the result of plant- Pest Around Homes ing infested sod, but infestations and in Noncrop Areas may also result when infested soil Wild garlic is unsightly around is used for fill or when building homes and gardens, on roadsides, is done on a garlic-contaminated and in noncrop areas. site. It also gives lawns a disagree- Spread of wild garlic seed and able odor. When heavily infested aerial bulblets by wind is of minor lawns are mowed, garlic odor significance. Spread of aerial becomes intense in the general bulblets by water, on the other area of the lawn, on the mower, hand, probably accounts for wide- and on the clothes of the person spread infestations on lands sub- mowing the lawn. ject to flooding.

CONTROL AND ERADICATION

Where a few plants of wild and most of these plants can be garlic are found, eradication can killed by repeated tillage or with be obtained by removing the several applications of herbicides. plants and all underground bulbs. However, hardshell bulbs that re- Because garlic bulbs are not killed main dormant in the soil for as by uprooting, they should be long as 5 or 6 years will continue burned or destroyed by some to reestablish the garlio stand other method that will kill the {8). This means that tillage or growing points. herbicide treatments may have to be continued for as long as 6 years Where wild garlic infestations or more to eradicate wild garlic. are extensive, eradication is difficult. Central bulbs, soft offset Cultural Control bulbs, and aerial bulblets will germinate during the fall of the Wild garlic is not easily killed year in which they are formed. by tillage because it possesses a

14 great deal of food reserves and of these bulbs were still viable reestablishes itself and resumes after 2 months (23). Hardshell growth after tillage. Lazenby bulbs attached to the dried soft (23) evaluated the effects of till- offset or central bulbs seemed to age and disturbance on wild garlic persist. growing in England. He found Wild garlic bulbs are also able that plants with large bulbs re- to tolerate deep planting ; and soft mained green for 7 weeks when offsets and central bulbs often allowed to lie on dry soil exposed emerge from a depth of 16 inches to high temperatures. The more (21). Deep planting, however, re- frequently the plant was dis- duced the number of offsets and turbed, so the roots were broken scapes produced on all bulbs. All from the soil, the more the size plants from soft offsets and cen- of the plant was reduced. tral bulbs planted at a depth of Repeated pulling and replant- 2 inches or less produced scapes, ing of growing plants reduced but the percentage of scapigerous the number and size of under- plants that were produced de- ground bulbs (23). Plants that creased as depth of planting in- had originated from aerial bulb- creased. Deep-planted hardshell lets were stimulated by one pull- bulbs had fewer scapes and off- ing in mid-March and increased sets than shallow-planted bulbs, in size. Uprooting the plants every but, in addition, length of dor- 2 weeks and immediately replant- mancy of hardshell bulbs in- ing them over a 4-month period creased as the depth of planting did not kill the plants, but yields increased. Nearly all hardshell of the underground structures bulbs left on the soil surface or were reduced. planted Y^ inch deep sprouted The date on which a disturb- after 2 years, but when planted ance took place influenced the at depths of 8 and 16 inches, half ability of the plant to recover of them remained dormant (21). (23). When disturbed on March Because aerial bulblets are 15, plants originating from aerial smaller than other bulbs, they do bulblets remained green for 4 to not have the food reserve to 5 weeks before death ; but during emerge from great depths. There this time, food reserves were ex- was a large reduction in the num- hausted in the production of new ber and weight of reproductive bulbs. Plants disturbed in April structures on plants developed or June immediately transferred from bulblets planted at a depth their food reserves into a small of 4 inches or more (21). bulb varying from one-half to Experiments show that time of three-fourths of the size of the tillage is important and that till- original bulblet. age should be repeated each time Soft offset bulbs and central new growth appears. Repeated bulbs lying on the soil surface for tillage is necessary to reduce re- 2 weeks began to shrivel, but some production of bulbs because the

15 wild garlic plant, even when dis- The effects of competition on turbed, is able to translocate wild garlic was studied by Laz- material to new bulbs. Deep plow- enby (19,20). Ryegrass (Lolium ing is only partially effective be- multiflorum and L. perenne) sown cause wild garlic can sprout and with aerial bulblets did not affect grow from great depths. the establishment of wild garlic, Tillage should be done after but competitive effects of the rye- emergence because tillage before grass later reduced the growth plant emergence merely redis- rate of wild garlic and reduced tributes bulbs and does nothing the weight of its underground toward control. This principle parts to one-fifth of those grown was recognized by Tinney (S5), alone (19). Competition from who recommended an annual wheat reduced the size of garlic plowing in November for 6 years plants and the weight of their followed by frequent cultivations underground parts (20). After 7 in spring. Frequent tillage gradu- years of competition from Pha- ally exhausts food reserves and laris tuberosa, wild garlic lost its if continued, eventually prevents vigor, and the plants grew only reproduction of underground 3 inches tall and failed to produce bulbs. scapes (3). An immediate effect of tillage Frequent mowing, beginning in is preventing the production of April, reduced the size of garlic plants and the weight of their scapes bearing aerial bulbs. underground parts (2Í). Close Deep plowing in fall to com- cutting was more injurious to pletely bury garlic plants followed garlic than high cutting. Cutting by shallow plowing in the spring in April was more effective than has been recommended in Illinois cutting in June. and Indiana (27,28). Clean tillage during spring and summer following plowing was then recom- Chemical Control mended. Because of the difficulty of con- Talbot (3i>) recommended the trolling wild garlic with cultural growing of row crops that could methods, much attention has been be tilled to cut off the garlic given to the possibility of chemi- plants. cal control. Control of wild garlic Lazenby (22) showed that time with chemicals has been attempted of tillage for planting cereals had for about 60 years. In the early important effects on garlic. Till- 1900's crankcase oil, carbolic acid, age for spring cereals reduced sulfuric acid, fuel oil, orchard the number of plants, the number heating oil, sodium chloride, and of hardshells, the number of sodium arsenite were tried on plants bearing scapes, and the size wild garlic (28). These materials of central bulbs and soft offset were unsatisfactory because they bulbs compared with tillage for killed the associated crop. fall-planted grains. Although the effects of tillage

16 have not been directly compared Davis and others (9) evalu- with the effects of modern-day ated a number of herbicides and herbicides, the nature of herbicide showed that 15 pounds per acre activity indicates that herbicides of dalapon, 6 pounds per acre of are more effective than tillage MH, 6 pounds per acre of ami- (9). Plants of wild garlic treated trole, 4 pounds per acre of 2,3,6- with 2,3,6-TBA (2,3,6-trichloro- TBA, and 2 pounds per acre of benzoic acid), or 2,4-D [(2,4- 2,4-D gave reasonable control of dichlorophenoxy) acetic acid] were wild garlic. In this study, the killed, and the hardshell and soft ester of 2,4-DB at 4 pounds per offset bulbs attached to the plants acre gave fair control of wild usually showed growth modifica- garlic. tions and often were killed (9). Because of low rates of appli- Central bulbs were more fre- cation needed for control (1 to quently killed than other bulb 2 pounds per acre) and relatively types. Herbicides were trans- low cost, 2,4-D has been investi- located through the plants to the gated extensively. The esters of underground reproductive parts. 2,4-D have been more effective Many herbicides have been than the amines, perhaps because evaluated for use on wild garlic. the esters penetrate the wax on Dalapon (2,2- dichloropr opionic wild garlic leaves better than do acid), TCA (trichloroacetic acid), the amines. MCPA ( [(4-chloro-o-tolyl)oxy]- Time of herbicide treatment in- acetic acid), amitrol (3-amino-s- ñuences the amount of kill ob- triazole), 2,4,5.T ( (2,4,5-trichlor- tained on wild garlic. More garlic ophenoxy) acetic acid), MH (1,2- plants receive treatment when dihydro - 3, 6 - py riadzinedione ), herbicide is applied after March 2,4-DB (4-(2,4-dichlorophenoxy) 15 than when applied earlier, be- butyric acid), and dicamba (3,6- cause wild garlic begins to emerge dichloro-o-anisic acid) have given in late summer and continues to some control. The rates and effec- emerge until March (11). How- tiveness of herbicides vary from ever, early treatments will kill location to location. wild garlic plants before new None of the herbicides that bulbs have been developed in the were available through 1974 elim- axils of the lower leaves. Forma- inated wild garlic in a single ap- tion of new bulbs usually becomes plication. Even when tops of apparent sometime in February. garlic plants were killed com- In the case of 2,3,6-TBA and pletely, viable hardshell or soft dicamba, time of application may offset bulbs often remained in the not be as critical as with 2,4-D soil and the garlic stand was not because they remain in the soil eradicated (8), Raleigh (29) re- for some time and are probably ported germination of soft offset absorbed over a period of time by bulbs after 3 successive years of the root system of the garlic top kill with 2,4-D. plants; thus plants that are not

17 up at the time of a fall applica- desirable turf legumes, such as tion will not receive a foliage white clover, as is 2,4-D. Most application but the herbicides established grasses will tolerate may be absorbed by the roots of treatment with either of these the garlic plant. two herbicides at 1 to 2 lb/A, but Herbicides can be used to keep either herbicide may kill or injure wild garlic under control. State seedling grasses. extension personnel should be Many species of trees, shrubs, consulted regarding herbicides flowers, and vegetables may be for specific problems. injured or killed if contacted by small amounts of 2,4-D or 2,4-DB. Chemical Control in Turf The hazard to nontarget plants is and Pastures much greater if spraying is done Several herbicides, at rates when wind is blowing, or when tolerated by one or more species highly volatile esters of the herbi- of turf plants, will control or cides are used. suppress wild garlic. Dicamba or 2,3,6-TBA are Either 2,4-D or 2,4-DB applied often more effective than 2,4-D at 1 to 2 lb/A two times a year for control of wild garlic. will control wild garlic. The addi- Dicamba and 2,3,6-TBA, however, tion of a surfactant to the spray persist in the soil longer than solution usually increases the 2,4-D and are more likely to in- effectiveness of the treatment. jure or kill woody ornamentals Treatments made in November by contact and entry through or early December and repeated roots in the soil. Both of these in February or March have herbicides are likely to injure or usually been more effective than kill nongrass plants if the herbi- treatments applied on other cides are applied to the soil sur^ schedules. Neither chemical will face over the root zone of sus- provide good control if top growth ceptible plants. Turf legumes are of the wild garlic has been re- usually killed or severely injured moved by recent mowing or graz- by rates of dicamba or 2,3,6-TBA ing. Also, mowing or grazing dur- that will control wild garlic, but ing the first week after treatment established grasses will tolerate may decrease the effectiveness. rates that control wild garlic. Good control has seldom oc- Treatments discussed for con- curred in less than 2 years of trol of wild garlic in turf will also treatment. Because hardshell control wild garlic in pastures. bulbs may continue to sprout for There are differences, however, as long as 5 years, annual treat- in the situations that need careful ments would be necessary until consideration. For example, leg- eradication is achieved. Wild gar- umes are more likely to be pres- lic is controlled more effectively ent as desirable plants in pasture by 2,4-D than by 2,4-DB, but than in turf. Registrations for 2,4-DB is not as likely to kill uses of herbicides in pastures

18 often differ greatly from registra- at 3 to 6 lb/A. Of these herbicides, tions for use in turf where graz- dicamba, MH, or amitrole would ing animals are not involved. be the most likely to cause slight to moderate injury of grasses. Dicamba or 2,3,6-TBA would Chemical Control in Small often kill or injure trees or shrubs Grain Fields with roots growing under the area Application of a low-volatile to be treated. ester of 2,4-D at 1/2 to % lb/A Dalapon at 4 to 8 lb/A effec- will often prevent small grains tively controls wild garlic, but from being graded garlicy. This will injure or kill grasses grow- rate of 2,4-D will not consistently ing at time of treatment. kill wild garlic, but it does reduce production of aerial bulblets and knock down tops of wild garlic so Precautions that the grain combine will gather Some herbicides are poisonous few, if any, bulblets during to man and animals. Read and harvest. follow the directions on all herbi- Fall-planted small grain will be cide labels and heed all precau- injured by application of 2,4-D tions. in the fall. Application of 2,4-D Keep herbicides in closed, well- in the spring after the grain has labeled containers in a dry place. tillered but before rapid elonga- Store them where they will not tion or jointing of the stems contaminate food or feed, and occurs seldom causes significant where children and pets cannot injury to small grains. Treatment reach them. before tillering or when the grain Avoid repeated or prolonged crop is in the boot stage usually contact of herbicides with the reduces grain yield. Oats are more skin. Avoid spilling herbicides on susceptible than barley, and bar- your skin, and keep them out of ley is more susceptible than the eyes, nose and mouth. If any wheat, to 2,4-D damage. is spilled on skin or clothing, wash it off the skin and change clothing Chemical Control immediately. in Waste Areas To protect fish and wildlife, do The vegetation that is to re- not contaminate lakes, streams, main on the site is a crucial factor or ponds with herbicide. Do not in selecting herbicides for control clean spraying equipment or of wild garlic in such waste areas dump excess spray material near as ditchbanks, drainageways, and such water. other noncrop areas. Avoid drift of herbicide sprays Grasses will generally tolerate to nearby crops and other desir- low-volatile esters of 2,4-D at able plants. 2 lb/A, 2,3,6-TBA or dicamba at Empty containers of poisonous 2 lb to 4 lb/A, or MH or amitrole chemicals are particularly hazard- 19 ous. Burn empty bags and card- bury them. Crush and bury bottles board containers in the open or or cans.

PARASITES AND DISEASES Although wild garlic is grazed ports Botrytis present in the Brit- readily, it is not seriously injured ish Isles. The disease causes dete- by animals. We have found that rioration and decay of the central aerial bulblets on the soil surface and soft offset bulbs and some- or other bulbs growing near the times may attack immature hard- soil surface may be eaten by field shell bulbs. The hard coat of the mice when this rodent population hardshell bulb may be a factor in is high. Richens (31) reports that preventing invasion of the fungus. bulb tissue may be eaten by slugs At points of fungi infection, a (Agriolimonx agrestis L.), milli- dark bluish color is apparent. pedes, and nematodes {Anguililla Richens (31) states that rot- Una dipsaci Kuhn). Widespread ting of young bulbs can some- damage from insect pests has not times be caused by Pénicillium been reported on wild garlic, but and Fusarium species. Sclerotium Freeman ^ reported damage to cepivorum Berk also attacks the soft offset bulbs from the cabbage central and soft offset bulbs of maggot. garlic as well as immature hard- At the Missouri Agricultural shells (31), Fine white mycelium Experiment Station, much dam- covering the surface of the bulb age to soft offset bulbs was found characterize the infection. Later during the summer of 1964 from in the season, black sclerotia fill insects tentatively identified as the cavity left by the rotting the cabbage maggot (Hylemya bulbs. Both Botrytis and Sclero- brassicae Bouche) and onion mag- tium may attack the plant at the got (H. antiqvxi Meigen). same time. Leaf spot (Heterospo- Several fungi have been re- rium aim Ell. and Mart.) has ported to attack wild garlic. been reported on wild garlic in Infestations of Botrytis (dUi Delaware, Illinois, and New Jer- Munn. have been observed in sey (36). Missouri. Richens (31) also re- The diseases cause serious dam- ' Personal communication from J. F. age to garlic plants in small local- Freeman, Kentucky Agricultural Ex- ized areas, but the diseases do periment Station. not become epiphytotic.

20 LITERATURE CITED

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