;B 603 G5 Jopy 1 (¥5™OIRL5 CLU5 WORK of flie Home OarJen G.5 United states Department of Agriculture And 3tate Colleger of Agriculture Cooperating Department Circular 35 *3^j5i»- CONTENTS Page General crop pests 3 Cutworms 3 Wirevvorms 4 Blister beetles 4 Grasshoppers 4 Red spiders 4 Slugs and snails 5 Damping off 5 Principal insects and diseases that attack gar- den crops 5 Beans 5 Pod-spot or anthracnose 5 Blight 5 Weevils G Bean-leaf beetle Bean aphis 7 Beets •. 7 Leaf-spot 7 Flea-beetles 7 Beet webworm 8 Cabbage 8 Black-rot 8 Yellows 9 Black-leg Club-root 10 Common cabbage worm 10 Cabbage looper 11 Harlequin cabbage bug 11 Plant-lice 11 Flea-beetles 12 Cabbage maggot 12 Cucumbers, muskmelons, and squashes. ... 13 Wilt 13 Mosaic 13 Anthracnose 14 Downy mildew 14 Leaf-spot 15 Striped cucumber beetle 15 The twelve-spotted cucumber beetle 16 The melon aphis 16 The common squash bug 17 The squash- vine borer 17 Onions IS Smut IS Onion thrips 10 Onion maggot 19 Peas 19 Pod-spot 19 Pea weevil 19 Page Principal insects and diseases that attack gar- den crops — Continued. Four-spotted bean weevil and cowpea wee- vil 20 Pea aphis 21 Potato ,. 21 Scab 21 Early-blight 22 Late-blight 22 Tip burn 22 Wilt 22 Colorado potato beetle 23 Blister beetles 23 Flea-beetles 23 Sweet potatoes 24 Black-rot 24 Stem-rot 24 Foot-rot 24 Tortoise beetles 24 Flea-beetles 25 Tomato 25 Leaf-spot 25 Wilt 25 Blossom-end rot 25 I'omato hornworms 25 Tomato fruitworm 26 Flea-beetles 26 How to rnake fungicides and insecticides 27 Fungicides 27 Bordeaux mixture 27 Formaldehyde 28 Insecticides 28 Lead-arsenate 28 Other stomach poisons 29 Nicotine sulphate 29 Kerosene emulsion 29 Soap sprays , 29 Lime 29 Flowers of sulphur 29 How to spray 29 Spraying and dusting tools 30 Miscellaneous control methods 30 Soil treatment 30 Carbon disulphid 30 Trap crops 31 Insect friends 31 Ladybird beetle 31 Syrphus fly 31 Contribution from the States Relations Service (Office of Extension Work North and West) A. C. True, Director NOV 17 1933 UtvuilON Of O0CUKENT8 ^ DISEASES AND INSECTS OF THE HOME GARDEN \ W. W. Gilbert, Pathologist, Bureau of Plant Industry, and C. H. Popenoe, Assistant Entomologist, Bureau of Entomology FROjNI the time the seeds of garden crops are put into the ground until the crops are gathered, diseases and insects may appear that must be fought. The gardener who starts with a clean soil has done much to keep out insects and diseases, and thus save the trouble and cost of applying sprays. "Prevention is better than cure," especially in the home garden, which usually must be planted on the same ground year after year. Many diseases and insects live over winter in the soil and will appear on the plants again next season if they are put in the same place. One of the best ways to help get rid of such troubles is to plant each vegetable in a different part of the garden every year. Some of the worst garden troubles are brought in on roots of plants, and remain in the soil to attack the next crop, consequently in buying plants of any kind, one shoidd be sure they are healthy and free from insects. The roots should be clean and hairy, not swollen or knotty. In giving ways of controlling insects and diseases in the following pages, they are grouped under two headings, treatment and prevention. Treatment means the use of methods of control which may be applied after the diseases or insects have appeared in the garden, such as hand- picking of insects, or spraying for diseases and insects. Prevention means the use of such methods of control as will prevent the development of insects or diseases, or their being carried over to crops the next year, such as burning sick plants, the use of seed free from disease, treatment of seed to kill insects and diseases, or the planting of crops on parts of the garden free from disease. Injurious insects may be divided into two classes. First, those which ordinarily attack only one crop or crops of one kind. The large tomato worm, which confines its feeding to the plants of the tomato and potato family, is an example of this class. The second class eats nearly every kind of plant that grows in the garden. Cutworms, several other caterpillars, several kinds of leaf-beetles, flea-beetles, plant-lice, thrips, and blister beetles are examples of this class. GENERAL CROP PESTS CUTWORMS. — Cutworms appear in great numbers in the early spring and summer, and jjlants may be killed before the gardener notices their presence. The main injury done is the cutting off of the stems of young plants at the surface of the ground. One cutworm can kill many plants in one night. Treatment. — The best remedy is poisoned bait. This can be made for use in a small garden by thoroughly mixing 2 level tablespoonfuls of white arsenic or paris green into 5 pounds of dry bran. Then add from 4 to 6 quarts of water in which a half pint of sorghum or cheap 3 4 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE molasses has been mixed. After the mash has stood for several hours, scatter it thinly over the garden or about the bases of the plants that have been set out. Put out the poison late in the day so that it Avill be moist during the night when the cutworms feed. Do this two or three times if the cutworms continue to cut the plants. A RSENIC and paris green are deadly poisons. Handle ■^^ them with great care. Keep young children, live- stock, and chickens away from this bait. Cutworms can be gathered by hand. Dig into the ground around the plants that have been cut off and the gray smooth cutworms will usually be found curled up about an inch below the surface of the ground. Sometimes several may be found around one plant. WIREWO RMS.— Wire worms are common pests in the garden. They are long, slender, hard, brown worm-like larvse, the young of snapping beetles or "snap bugs." They attack and often do great damage to pota- toes, carrots, beets, sweet pota- toes, and onions. Prevention. — Deep midsummer cultivation and heavy fertilizing will reduce wireworm damage. BLISTER BEETLES. — Blister beetles are common farm pests and are very destructive to vege- tables, especially peas, beans, potatoes, and beets. They travel like army w^orms, and for this reason are sometimes called army beetles. They are hungry feeders, and often travel in lines, eating everything in their path. They are slender in form, somewhat soft-bodied, and of many colors. Some are entirely black, some are yellow with black stripes, some are gray, and others are gray spotted with black. Treatment. — When the beetles are first seen, spray with lead arsenate (see page 23). Hand-picking is somewhat dangerous unless gloves are worn, as the beetles may blister the tender skin. GRASSHOPPERS. — Grasshoppers are often troublesome to vegetables. Treatment. — Use the same bran mash as for cutworms (see page 3), adding one finely chopped orange or lemon to the water before mixing. RED SPIDERS. — Nearly all ^•egetables are attacked by what are Fig. 1. — Bean anthracnose on pod and seeds. DISEASES AND INSECTS OF THE HOME GARDEN 5 commonly called red spiders. This is not a true spider, but a mite, and is so small that it can hardly be seen. It injures plants by sucking the juices, and when plants are neglected their strength is slowly lost and in time they die. In case of a bad attack, great numbers of the mites can be found on the leaves, and the webs Avhich the insects spin from plant to plant can be seen with the mites themselves passing rapidly over them and gathering in swarms. Sometimes the plants look as though scorched by fire. Treatment. — Spraying with soap and water (see page 29) or kerosene- soap emulsion (see page 29) is a good remedy. Another is spraying with flowers of sulphur mixed with water. (See page 29.) Watch for these pests, and spray when they first appear, as it is hard to save the plants after they are covered with the webs. SLUGS AND SNAILS. — Much harm is done by slugs — soft, slimy animals which look like snails without shells. They are black, gray, or brown, usually spotted with black, and grow to be 5 or 6 inches long. Snails also are sometimes troublesome. Attack is worst on young ])lants grown in hotbeds and cold frames. Tender garden vegetables of nearly all kinds are also injured by snails and slugs out of doors. Treatment. — The best remedy is air-slaked lime (see page 29) sprinkled over the plants and scattered about the garden. When the lime gets on the slugs, they throw off so much slime that they become weakened and die. Other remedies are soot, road dust, and sifted wood ashes. A strip of soot or wood ashes around the garden will keep the slugs away. Prevention. — To avoid slugs, remove all rotten wood and old struc- tures and keep the entire garden and yard free from rubbish of all kinds. DAMPING-OFF. — When seeds of tomato, cabbage or other vegetables are planted in small boxes in the house to raise early plants for setting in the garden, a disease called "damping-off " often causes much trouble. Small plants may suddenly fall over and die, or black dead areas may appear on the stems near the soil, which dwarf or kill the plants. Treatment. — Give the plants plenty of air and light and water moder- ately early in the morning. Prevention. — The best method of preventing damping-off and root troubles which may attack small plants is to treat the soil in the seed box with boiling Avater a few days before planting the seeds. (See page 30.) This Avill kill the diseases and insects present. PRINCIPAL INSECTS AND DISEASES THAT ATTACK GARDEN CROPS BEANS POD SPOT or ANTHRACNOSE.— Most gardeners recognize anthracnoso b}' the roundish sunken spots with reddish edges which it causes on the young pods (fig. 1). It also makes red spots on the stems and leaf veinc, and grows through the pods and causes rusty looking sores on the ripe seeds. The disease lives over winter on the seeds. Prevention. — See blight below. BLIGHT. — Bean blight shows on the pods first as Avater-soaked looking spots. These later become rust colored. On the lea\^es it causes large 6 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE patches to turn yellow, then brown, and die (fig. 2). This disease is also carried on the seed. Treatment. — There is no successful treatment. Prevention.- — The best way to avoid both anthracnose and blight is to plant only healthy, unspotted seeds in a part of the garden where beans were not grown the previous year. Save seed for next year from pods free from spots. WEEVILS. — The worst insect enemies of beans are weevils. Attack begins in the field, from eggs laid in a joint of the pod or an opening through which the egg is pushed. The eggs hatch into the larvae, or grubs, which grow inside the bean and soon after the beans are har- vested change to weevils and begin to come out (fig. 3). A second brood of the common bean weevil may be enough to Fig. 2. — Bean blight on leaf and pod. ruin a crop of beans for either human food or seed. Sev- eral broods may be produced in a year. The com m o n bean weevil is dull gray Avith reddish legs and is about one-eighth of an inch long. Treatment.— Bean wppvils Pinnnf hp ^^^' ^' — '^'^'^ common bean weevil: a, full-grown beetle; b, grub; f, pupa (sleeping stage). Greatly enlarged. The small straight controlled in the line between a and c shows length of a full-grown weevil. field. They breed in dry seed and it is, therefore, best to harvest the crop, and as soon as dry to fumi- gate it with carbon disulphid. Carbon disulphid is explosive, so the club leader or parents should supervise the use of it, as ex- plained on page 31. Prevention. — Plant only seed free from weevils. BEAN LEAF -BEETLE. — The . ^ ,, bean leaf-beetle (fig. 4) does / ^' \ ^ much injury in the Eastern I'^'^;- ■*. — The bean leaf-beetle: a, full-grown beetle; h, Q. ■ A t^ aU' 4-1 ] Pi'pa; c, grub. Greatly enlarged. Small straight line Otaies ana rroni UniO SOUtllWarcl between o and b shows length of full-grown beetle. DISEASES AND INSECTS OF THE HOME GARDEN to Louisiana. The beetles eat large round lioles in the growing leaves. They also feed on such wild plants as beggarweed or tickseed. The grubs feed on the roots and main stems just below the ground, their habits be- ing much the same as those of the better known cucum- ber beetles. Treatment. — Lead arsen- ate is the best remedj^ for this insect. On young beans it must be applied at half strength in order not to burn the plants. Direc- tions for mixing this poison are given on page 28. BEAN APHIS. — The bean aphis is a very small, black- ish plant-louse which does damage in all parts of the United States, being very troublesome in California, where it works on the early plants. Treatment. — Nicotine sul- phate (see page 29) is the best remedy if put on as soon later, if found necessary. Fig. 6. — The beet flea-beetle: a. beetle; b, pupa; c.fullgrowngrub. Greatly enlarged. Fig. 5. — Beet leaf showing the beet leaf-spot. as the plant-lice are first seen and again BEETS LEAF-SPOT . — In leaf-spot numerous small, dead spots are present on the leaves. These spots are roundish and have 8 white center and a purple edge (fig. 5). Treatment. — The trouble can be con- trolled by spraying with Bordeaux mix- ture (see page 27). Begin to spray when the disease appears and repeat every 10 days until the end of the season. FLEA-BEETLES. — The beet flea-beetle (fig. G), also called the spinach flea-beetle, is very injurious to table beets, attacking them as soon as they are above the ground. The young, or larvae, grow on chickweed and pigweed, and a second brood attacks the beets. The young DEPAFiTMEXT C'lItflTLAR 35, IT. S. DEPARTMENT OF AORIC'ITLTURE Fig. S. — Cabbage black-rot. Slice across a diseased stem to show the black ring which the disease causes. sometimes })ecome so thick as to destroy en- tire rows of beets before the insects are even seen by the gardener. They even work down and bore into the crowns of the plants. Treaimeni. — This insect can be kept down readily by spraying with arsenate of lead (see page 28) w-hen the pest is first seen, and again as often as needed. Prevention. — Chick- weed and p i g w e e d (lamb's-quarters) are the natural food plants Fig. 7.— Beet webworm: o, moth; ^f the flea-beetle, and 6, full-grown larva. Enlarged. should be killed in the early spring. Cutworms also feed on these weeds. BEET WEBWORM. — Several kinds of web worms attack beets b}- eating the leaves, which become webbed together on the growing plant. The worst of these pests is shown in figure 7. Treatment. — Spray with arsenate of lead, made as described on page 28. Prevention. — The garde n should be kept free from such weeds as pigweed, since these encourage M^ebworms and help them to spread. CABBAGE The diseases which attack cabbage also attack other plants of the cabbage family, such as cauliflower, brussels sprouts, and turnips. BLACK-ROT.— Cabbage plants attacked by the black-rot look sickly and do not groAV well. They usually have yellowed leaves with blackened veins. The inside of the stem shows a blackened ring (fig. 8) and the heads frequently rot in the field. Plants may be attacked by black-rot at any time during their growth. Serious losses often result from this disease. Treatment. — Thereis no treat- ment which will stop the dis- ease. Pull and burn sick plants. Prevention. — To prevent this trouble soak the seeds for 15 -This cabbage plant is one-sided, stunted, and the . , • , i p i .• leaves curled because of yellows. mmutCS, JUSt bctorC plautmg.m Fig 9. DISEASES AXD INSECTS OF THE HOME GARDEN a solution of 1 teaspoon- ful of formaldehyde to 1 quart of water. (See page 28.) Plant in soil free from black-rot. Set the plants in a part of the garden which has not been in cabbage or any other plant of the cab- bage family for a year or more. YELLOWS. — Yellows or wilt attacks the plants while small, and causes a black ring in the stem, like black-rot. The plants turn yellow- ish-green, but unlike black-rot the leaves fall off. Often one-sided leaves or plants are found (fig. 9). Many plants attacked dry up and die young, and very few sick plants form -Cabbage plant with large knotted roots caused by club root. Fig. 10. — Black-leg makes the cabbage stem turn black and stunts the entire plant. A few feeble side roots are developed above. heads. In many localities wilt is the most important cabbage disease and does a great amount of damage. Treatment. — None. Prevention. — The use of varieties which do not have this disease is the best method of prevention. If possible, set healthy young plants in a part of the garden where the disease has not appeared. BLACK-LEG. — Black-leg may at- tack cabbage plants while they are very small, often in the seed bed. The disease gets its name from the fact that the stem of the plant rots and turns black (fig. 10). It also causes dark spots on the leaves. These dead spots are later covered with tiny black pimples. In the early stages of the disease, the leaves often turn purple. Later the whole plant wilts and the tips of 10 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE Fig. 12. — The common cabbage worm: above, butter- fly; below, cabbage worm, c, and chrysalis, N- FiG. 1.5. — The seod-corn maggot: a, back view of fly; 6, side view; r, pupariiim; h Fig. 21. — Striped cucumber beetle: a, beetle; b, root- worm; c, pupa. Small line at right of beetleis natural length. Fig. 22. — Barrel hoop and cheesecloth cover for cucumber and squash plants to keep insects off. 10 DEPARTMENT CIROTTLAR 35, TT. S. DEPARTMENT OF AORIClTLTr^RE Fig. 23. — Twelve-spotted cucumber beetle: a, beetle; b, egg c, root-worm; e, work of root-worm on corn root;/, pupa Small lines at right show natural size. made by placing the halves of a barrel hoop, as shown in figure 'ii, and co\ering the frame thus made with cheesecloth. A good grade of cheese- cloth must be used, as the beetles can easily go through a cheap mosquito- netting, and a material heavier than cheesecloth keeps the light from the plants. The lower edges of the cloth must be held down tightly to the ground by stones or other weights or the beetles will burrow underneath. Cheesecloth- covered frames of any size and shape desired can be made from four 1-inch square corner pieces to which strips of lath are nailed. Another method is to di- vide the hill into quarters, and each week plant in one of the quarters enough seed for a full hill. In this way, even though the insects attack some of the plants, there will be enough left to give a crop. Arsenate of lead (see page 28), as used for the Colorado potato beetle, is the most effective remedy to use against this insect. Bordeaux mixture with lead arsenate added (see page 28) dri^'es away the beetles and j^re- vents injury to the leaves so treated. THE TWELVE-SPOTTED CUCUMBER BEETLE. — The twelve-spotted cucumber beetle (fig. 23) is a little larger than the striped cucumber beetle. It often eats the cucumber leaves, causing much injury. The larva lives mainly on grasses and corn. Treatment. — Spraying with lead arsenate (see page 23) and treating in the same manner as the striped cucumber beetle are the best remedies for this insect in small gardens. THE MELON APHIS. — The melon aphis (fig. 24), com- monly called the melon louse, is very small, and greenish, or nearly jet black. It injures cucumbers and many other plants by sucking their juices. It occurs from early spring and summer to late autumn di • , X Fig. 24. — The melon aphis or louse, s _ early winter. In seasons ^,_ ^.^^^^ ^^^,^^^. ,, ^^^^om young; which favor its increase, par- d, wingless female. Much enlarged. howing c, nym : a and ph stage; DISEASES AND INSECTS OF THE HOME GARDEN 17 ticularly in summers following springs that are cool and rainy, it often appears in great numbers and does much damage, gathering in masses on the under side of the leaves of plants, and causing them to curl, shrivel, and lose color, and stopping the growth of the fruit. It often kills the plants outright. An attacked melon plant is shown in figure 25. The melon aphis, like others of its kind, gives ofi^ honeydew, a honey-like juice. When the aphids become very thick, the honeydew covers the leaves with a thin sticky coating on which the white skm^ ot the plant-lice stick, and this attra( t^ attention to the injury, as do also the wilt- ing and dying of the plants. Treatment. — The best rem- edy is spraying nicotine sul- phate (see page 29). THE COMMON SQUASH BUG. — Squashes, gourds, and ]uimpkins suffer from the same pests as cucumbers. If the plants escape the striped cucumber beetle and the melon aphis, they may be damaged by the squash bug (fig. 26, p. 18), commonly known as the stink bug from its disagreeable odor. Like the melon aphis, it feeds on the plant juices. Treatment. — Hand picking before the insect lays its eggs is of value. The eggs, which are shiny brown, are easily seen on the under side of the leaves and can be crushed. Cover- ing the plants as for beetles and using nicotine sulphate (see page 29) are helpful, but the full-grown bugs are hard Fig. 25.— Melon leaves curled by plant-lice. to kill. They may be trapped by placing small pieces of board, shingle, or bark on the ground near the plants. The insects go under these pieces of wood to hide during the day. The traps should be examined each morning and the bugs found should be killed. THE SQUASH-VINE BORER. — After cucumbers and melons have made good growth, they are sometimes attacked by the squash-vine borer (fig. 27, p. 18), which, how^ever, is much more destructive to pumpkins and squashes, especially the Hubbard and summer bush varieties. This is the large white grub which bores through the stems, sometimes cutting them almost through near the roots. 18 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE Fig. 2G. — Tlie common squash bug: a, h, c, d, e, partly grown young; /, full- grown bug; g, eggs. Enlarged. Treatment. — When the borers attack cuciiniber.s, it is ahiiost impossible to kill them without killing the plants. The borers may be cut out of squash vines by slitting the stems of the vines lengthwise. After making the slit, portions of the vines should be covered. Help the plant to grow extra roots by covering damaged stems with earth. Keep the plants growing vigorously, and free from other insects and diseases. Prevention. — Plant early squash for a trap. Harrow the garden lightly in the fall, and plow deeply in the spring to keep the moths from coming out. The dead vines and old plants should be destroyed as soon as the crop is gathered. ONIONS SMUT. — S m u t causes the young onion ])lants to die back. The dead leaves are covered with pimples full of black powder. The disease lives over winter in the soil. Treatment. — There is no successful rem- edy for sick plants. Fig. 27. — Squash-vine borer: o, moth with wings spread; b, moth Prpiipntinri Plant at rest; c, egg on section of vine; rf, caterpillar or grub in squash . 1 ' J l vine; e, chrysalis; /.chrysalis cell from ground. Enlarged one-third. OniOUS Oil lanO. WUcre DISEASES AND INSECTS OF THE HOME GARDEN 19 the disease has not occurred. If this cannot be done, sprinkle formal- dehyde solution (1 teaspoonful to 1 quart of water) in the drill after the seeds have been dropped and before covering, using 3 to 4 quarts of the solution to each 100 feet of row. ONION THRIPS. — The onion thrips is a very small insect, often incor- rectly called the onion louse, which causes the injury known as white blast, white blight, or silvertop. It also causes seal- lions or thick-necks. This insect often ruins entire fields of onions. It also at- tacks cauliflower, cabbage, cucumbers, melons, pumpkins, squashes, parsley, tomatoes, kale, turnips, and seed beets. Treatment. — Nicotine sulphate (see page 29) is used with success. ONION MAGGOT. — The onion maggot (fig. 28) is the worst northern onion pest. It eats into the bulb, starting decay, and often destroys the whole onion. The onion maggot is the larva of a small gray fly, which looks like a small house fly. Two or three broods may be looked for each year. Treatment. — The best remedy known is a poisoned bait to attract and kill the flies. The bait is made as follows: Sodium arsenate I level teaspoonful Water 1 gallon Cheap molasses 1 pint Dissolve the sodium arsenate in boiling water, and add the molasses. Since it is not necessary to cover the leaves, the bait may be put on in large drops by shaking from a whisk broom dipped into a bucket ot the poison. It should be applied when the flies are first seen. Fig. 28. — Young onion plant, showing onion maggots at worlc in tlie bulb; at right, plant exposed slightly, showing the same. PEAS POD SPOT. — This disease gets its name from the round or irregular dark spots which it causes on the pods. It also makes spots on the leaves and dark, sunken places on the stems; often there are dark spots on the seeds from diseased pods. The disease is carried over from one year to the next upon such disea.sed seed. Treatment. — There is no effective treatment for the growing crop. Prevention. — Save seeds from unspotted pods. Plant only healthy seeds free from spots. Plant in a different part of the garden each year. PEA WEEVIL. — Seed peas are often found with a single round hole in each, due to attack by the pea weevil or pea "bug." This insect is about ^4 inch long and is thickly covered with brownish fuzz with black and 20 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE white markings. Often every pea in a pod when prepared for the table will be found infested with a weevil. In dry seed the hollowed out place under the skin in which the insect lives can be seen plainly. Many seeds that have been attacked will start to grow, but the plants are likely to be weak. Since this weevil has only one brood a year, it is treated more easily than is the bean or cowpea weevil. Prevention. — If you raise your own seed, keep it in a warm room in a tight bag or box for one full season before planting. The weevils will come out of the seed so kept and die. Do not plant seeds that have been injured by weevils. FOUR-SPOTTED BEAN WEEVIL AND COWPEA WEEVIL. — The four- spotted bean weevil and the cowpea weevil look much alike. While both like cowpeas as food, they also live on table beans in the South, Fig. 29. — Scab on potato. Unfit for planting. Fig. 30. — Spots of early-blight on potato leaf. and peas, chick-peas and, in fact, all such seeds large enough for them to grow in. They differ from the true pea weevil in that they have several })roods each year on dry seeds. Treatment. — Fumigate with carbon disulphid (see page 30), or if the /~^ARBON disulphid is explosive, and club members should ^^ use it only under the direction of the club leader or parents. DISEASES AND INSECTS OF THE HOME GARDEN 21 seed are not to be used for planting, place in a shallow pan and bake in an oven for 5 to 10 minutes. PEA APHIS. — The pea aphis is one of the largest of the j)lant-lice, being about one- eighth of an inch long. It is pea green, the same as its food plant. Attack begins upon the young vine, the lice gath- ering in clusters about the tips. Later they attack the stem and suck out the life of the plant. Treatment. — Nicotine sul- phate (see page 29) and kero- sene soap emulsion (see page 29) are good remedies if used when the insects first begin to attack the plants in early spring. The plant-lice can also be beaten off the vines on to the ground. This can best be done with a brush of small twigs or a pine bough with the leaves left on. On a warm, sunny day the lice are killed by >et b the hot ground on which they fall and few, if any, ever the plants. This aphis also feeds on clover, alfalfa, field peas, and several Fig. 31. — Potato leaves with dead spots due to late-blight. >ack to weeds. Fig. 32. — Potato tuber rutted by lute blight. POTATO SCAB. — This t r o u b 1 e causes roughened brownish s])ots or scabs on the skin of the potatoes (fig. 29). In severe cases the whole po- tato may be covered with these spots. The trouble lives in the soil and is carried on the scabby po- tatoes. Treatment. — The control of this disease is entirely j)reventive. P r ev entiov . — Do not plant scabby seed. Do 22 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE Fig. 33. — -Tip burn of potato leaves due to hot, dry weather. not use lime, fresh stable manure, or wood ashes for fertilizer. Plant on new land where scab has not been found before. If troubled with the disease, soak the seed potatoes, just before cutting, for 15 minutes in a solution of 1 teaspoonful formaldehyde in 1 quart of water (see page 28). EARLY-BLIGHT. — In the Northern States, this trouble usually comes in early July. It cau.ses dark, roundish spots on the leaves, which have ridges or rings (fig. 30). It is worse in moist, warm weather. Treatment. — Spray plants with Bordeaux mixture (see page 27), beginning when the disease is first seen. Repeat the spraying every 10 to 14 days in dry weather and every 7 days in moist weather to the end of the season. LATE-BLIGHT. — In the Northern States, this disease is the cause of great losses in years when cool, moist weather occurs during August. It causes dark, irregular dead spots on the leaves (fig. 31) and stems, and spreads very fast. In favorable weather, the plants may be Later, it pro- killed in a few days duces a brown rotting of the tubers (fig. 32), which continues after the potatoes have been put into the cellar. Treatment. — Late-blight can be controlled by carefully spraying the plants with Bordeaux mixture (see page 27) the same as for early-blight. This disease is more serious than early-blight and to control it the plants must be kept covered all the time with a coating of the spray mix- ture, which must be put on with a good sprayer which gives a fine misty spray. Potatoes showing rot at digging time should not be put in the cellar with the good potatoes. For planting, select only sound potatoes, since the disease lives over winter in diseased potatoes. TIP BURN. — In dry, hot weather the tips and edges of the potato leaves often curl up, turn brown, and die (fig. 33) from lack of water and too hot sun. Treatment. — Spraying with Bordeaux mixture (see page 27), as for early-blight, will help to prevent this trouble. WILT. — This disease causes a yellowing and slow wilting of the plants and reduces the yield. The disease causes a browning of the stem end of the potatoes (fig. 34). Fig. 34. — Potato stem-end browning due to wilt. Not fit to plant. DISEASES AND INSECTS OF THE HOME GARDEN 23 Treatment. — There is no remedy for sick plants. Prevention. — Dis e a s e d seed potatoes should not be used, because in this way the troul^le is carried to the plants. Do not plant on land where the disease was bad the year before. COLORADO POTATO BEETLE. — If careful watch is not kept, this in- sect (fig. 33) is sure to injure the crop. The beetle and its slugs, the young or larva, are so well known that no description is necessary. Both slugs and beetles feed on the potato plants. After passing the winter in the ground, the beetles appear about the time the potatoes come up, lay their eggs on the under sides of the leaves, and start feeding. They often destroy small patches grown for garden purposes. The beetles sometimes feed also on eggplants and tomatoes. There are from one to three broods a year. Treatment. — Arsenate of lead is the best remedy. Use as described on page 28. BLISTER BEETLES.^Blister beetles rank next to the Colorado potato beetle as potato pests. They are slim, some- what soft-bodied insects of difTerent colors, sometimes striped, that feed on all kinds of vegetables, seeming to pre- fer potatoes, after which they attack beans, peas, beets, cabbage and other plants. They are sometimes called "old-fashioned potato bugs." Treatment. — Lead arsenate is the best remedy, mixed and put on as recommended on page 28. FLEA-BEETLES. — Small round holes in the leaves of the potatoes and vari- ous related crops, such as tomatoes and eggplants, show the presence of flea-beetles. Treatment. — Lead arsenate (see p. 28) put on as a spray is the best remedy, especially if stirred into Bordeaux mix- ture. Bordeaux mixture (see p. 27) alone is an excellent spray to drive the beetles away. Spray both sides of Fig. 36. — Sweet potato slips showing . black-rot should not be set in the field. the leaVCS. 24 DEPARTMENT CIRCULAR '^fj, U. S. DEPARTMENT OF AGRICULTURE Fig. 37.- -End of sweet potato showing black ring caused by stem-rot. SWEET POTATOES BLACK -ROT. — This wide- spread disease causes round- ish, black, sunken spots on the potatoes. Diseased shps in the hotbeds show black spots on the stems (fig. 36, p. 23) or they may rot off and die soon after being set out. Blackrotted potatoes have a bitter taste when cooked. Treatment. — There is no ef- fective treatment for sick plants. Prevention. — To prevent black-rot, use fresh soil in the hotbeds. Select only smooth, sound potatoes for bedding and discard all diseased slips. Plant next year in a part of the garden where sweet potatoes have not been grown for several years. STEM-ROT. — The stem-rot occurs nearly everywhere sweet potatoes are grown. It is first indicated by the yellowing of the leaves, after which the plant gradually wilts and dies. Stems from diseased plants are black inside and the potatoes show a black ring (fig. 37). Treatment. — None. Prevention. — To prevent this disease, select seed for planting at digging time and only from healthy plants. If the plant stem is black inside, save no seed from that hill. For grow- ing slips, follow directions for prevention given under black-rot above. FOOT-ROT.— This dis- ease shows first about mid- summer as small brown or black spots on the stems fig.38. near the ground. These spots grow larger and become covered with many tiny black pimples. Finally they girdle the stems and the plants die. Treatment. — None. Prevention. — To prevent foot-rot, plant only healthy slips in a part of the garden not before in sweet potatoes. Follow directions for grow- ing slips given under black-rot prevention above. TORTOISE BEETLES.— There are several kinds of small beetles (fig. 38) which feed on sweet potato, and which are shaped much like turtles. -The golden tortoise beetle: d, beetle; 6, young. Greatly enlarged. DISEASES AND IVSEf'TS OF THE IIO\rE GARDEN 25 Ik^ ^^^V Fig. 39. — Tomato leaf-spot causes many small dark spots on the leaves, which turn yellow, curl up, and drop off. They are usually golden, marked with black. They and their young eat the leaves. The young are pecu- liar, spiny grubs with long forked tails which they carry over their backs loaded with dirt for protection. Trea t men t. — The grower need not spray for these pests unless they become serious. Use arsenate of lead (page 28). FLEA-BEETLES. — These are little, black, shiny beetles that hop about like fleas. They may not be seen unless looked for carefully. They cut long slits into the leaves or eat them full of small holes. Treatment. — Spray with arsenate of lead as directed on page 28. TOMATO LEAF-SPOT. — This disease causes many small dark spots with white centers on the tomato leaves (fig. 39). The bottom leaves are attacked first and soon turn yellow, curl up, and drop off. The disea.se is quite common and is usually first seen when the plants are about half grown. Treatment. — Thorough spraying with Bordeaux mixture (.see page 27) will hold the disease in check. Begin spraying as .soon as the plants are set in the garden and repeat every ten days. Prevention. — Grow plants in a different part of the garden each year. WILT. — In some States tomatoes are attacked by a wilt disease which ]jre vents the plants from getting water. Plants so attacked wilt and die suddenly without any apparent reason. Treatment. — None . Prevention. — Destroy diseased plants. Use new land for tomatoes the next year. Several excellent varieties of tomatoes resistant to this disease have been bred by the United States Department of Agriculture. BLOSSOM-END ROT. — This disease causes large, dark, rotten spots on the blossom end of the green fruits (fig. 40, p. 26). Treatment.— V^atenng the plants during very dry weather has been found helpful in controlling the trouble. TOMATO WORMS OR HORN WORMS. —These large green caterpillars are also called tobacco hornworms or tobacco worms as they feed on both 26 DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE Fig. 40. — Tomato blossom-end rot. these ])lants (fig 41). They are the young of hirge hum- ming bird moth.s and have a wicked looking horn on the tail. The worms are harni- le.'s to persons and so need not be feared. There are two broods in a season. Vs hen the worms become full £rown they may cut all the leaves from the tomato plants. The gardener should be on the lookout for the first as well as the second brood. Treatinent. — Hand picking is the best remedy, but it takes sharp eyes to see the worms when they are not moving since they are of the same color as the stems on which they rest during the day. They may often be discovered by their voidings. When feeding they are more readily seen and can be easily killed. A single dose of lead arsenate (see page 28) will kill them. Tomato worms will often be found that have many little white cases on their backs. These are not the eggs of the caterpillar, as it does not lay eggs. They are cases or cocoons from which come little wasps that sting and kill tomato hornworms. Do not kill hornworms that are carrying these cases, as the wa-sps will be killed also. TOMATO FRUITWORM. — The tomato fruitworni (fig. 42), also called the corn earworm, is the cause of much trouble to tomato growers as it eats into the ripening fruit and destroys it. Treatment. — Lead arsenate (see page 28) put on two or three times will keep the insect partially under control. As long as sweet corn is nearby, the worms will let the tomatoes alone. Hand picking is good in small gardens. FLEA-BEETLES. — The potato Sea,- beetle fre- quently attacks toma- toes and does much damage. Treatment. — Dip the young plants in a lead- arsenate solution (3 ounces of lead-arsenate paste in 1 gallon of water) before setting them out. Spraying with Bordeaux mixture (see page 27) will drive the beetles awa.y. Fig. 41. — Tomato homworm: a, moth; b, hornworm; c, chrysalis. DISEASES AND INSECTS OF THE HOME GARDEN 27 \j a Fig. 42. — Tomato fruitworm: a, full-grown moth; b, fruit worm. HOW TO MAKE FUNGICIDES AND INSECTICIDES Fungicides are materials used to kill germs or molds which cause plant diseases. Insecticides are materials used to kill insects which attack plants. TDECAUSE of the danger of poisoning from careless handling of these materials, it is desirable that the club leader or some adult be present when the solutions are made. This is especially true of lead-arsenate, paris green, and arsenic. FUNGICIDES BORDEAUX MIXTURE. — This is one of the best spray mixtures for controlling leaf diseases of garden plants. Since Bordeaux helps keep the diseases off the plants it is very important that it should be applied before they appear or as soon as they are seen. It can be bought in paste or dust form from seed dealers, or a better spray can be made at home, as follows: Bluestone (copper sulphate) 1 ounce Quicklime (stone lime) 1 ounce Water 3 quarts Dissolve the bluestone in 1>^ quarts of hot water in a wooden or earthen- ware pail. Slake the lime in a small quantity of water, then add enough more to make 1 J 2 quarts. Pour the bluestone and lime solutions together, straining them through a fine cheesecloth or brass wire strainer, and mix thoroughly. The mixture is Bordeaux. It should be made fresh each time used, as it is not good when old. Since stone lime air slakes rapidly and is then no longer good for Bordeaux, it is best to make up a stock solution of lime containing 1 pound of lime to each gallon of water. This will keep a long time. 28 DEPARTMENT CIRCULAR 35, U. «. DEPARTxMENT OF AGRICULTURE Fig. 43. — A small glass sprayer suitable for a small garden. A stock solution of bluestone can be made by dissolving 1 pound of the bluestone crystals in a gallon of water. A half pint of each of the.se stock lime and bluestone solu- tions will take the place of an ounce of lime and bluestone given in the formula. Dilute each with water as directed above before mixing. By adding 1 ounce of lead-arsenate paste or Yi ounce of powdered lead- arsenate to Bordeaux, the mix- ture made is useful for killing insects as well as controlling diseases. FORMALDEHYDE. — Formalin. This chemical is used to make a solution for soaking potatoes, seeds, and soil to kill disease germs. Use 1 teaspoonf ul to 1 quart of water or 1 ounce to 2 gallons of water. Formalde- hyde looks like water and causes the eyes to smart, but is not poisonous. INSECTICIDES Two kinds of insecticides are used for controlling insects, stomach poisons and contact poisons. Stomach poisons, such as lead and lime arsenate, and paris green, are used for all insects which injure plants by chewing the leaves or stems, like striped cucumber beetles and potato beetles. Contact poisons, such as kerosene emulsion and nicotine sulphate, which kill by touching the insects, are u.sed for sucking insects like plant lice and squash bugs. Stomach poisons are of no value for sucking insects. LEAD-ARSENATE. — Lead-arsenate is sold by most druggists and seedsmen both as a powder and as a paste. It is a good remedy for nearly all kinds of j)ests which eat the leaves of garden plants. Itisused either mixed with water as a spray or as a dry powder dusted on plants. HowtomaJcethe spray . r ,, N J • . u, . , , . —Take 1 level teaspoon- FlG. 44. — A compressed-air sprayer suitable for larger gardens and » i n i i i i small fruit trees. lul ot powdered lead- DISEASES AND INSECTS OF THE HOME GARDEN 29 arsenate for each pint of water. Mix thoroughly and apply with sprayer. If lead-arsenate paste is used, take 2 teaspoonfuls for each pint of water to make a spray mixture. Hoiv to mix dust poison. — Where a sprayer is not available, a dust may be used. This is made by thoroughly mixing 1 pound of pow- dered lead arsenate with 3 pounds of air slaked or powdered lime. This mixture is put into a cheesecloth bag and dusted onto the plants by shaking the bag lightly over them. OTHER STOMACH POISONS, such as arsenate of lime and arsenate of zinc may also be bought from dealers. These are used like lead- arsenate, either in paste or powdered form. Directions for making the mixtures will be found on the packages. NICOTINE SULPHATE.— For small gardens use a teaspoonful of nico- tine sulphate in a gallon of water. A 1-inch cube of hard soap should be shaved up and thoroughly' mixed into the solution. Full directions for mixing are given on the covers of the packages. For large insects like the pea aphis, a little more nicotine sulphate than stated above should be used. By looking carefully at the newly sprayed plants, one can tell whether there is enough soap in the mixture. If the spray draws together in drops, more soap should be added. When possible, resin fish-oil soap should be used, but cheap laundry soap will do. If the nicotine sulphate solution has stood for any length of time, it should be mixed thoroughly before using. The insects themselves must be wet by the spray or they will not be killed. Therefore, the spraying should be very thorough, and should be done as soon as the insects are noticed. KEROSENE EMULSION. — Several kinds of kerosene emulsion can be bought in the stores already mixed, so it is hardly worth while to make it at home for the small garden. SOAP SPRAYS. — Ordinary soapsuds is a good spray mixture for plant- lice and leafhoppers. It should be made by dissolving a 1-inch cube of laundry soap or a rounded tablespoonful of whale-oil or fish-oil soap in a quart of hot water. This also must reach the bodies of the insects to kill them. This spray must not be used full strength on very tender plants, such as young cabbage or cauliflower in seed beds, garden peas, or young beans, as it will injure the leaves. Use one-half strength for these plants. LIME. — Lime is used to control cabbage clubroot, but it is liable to increase scab on potatoes. It acts at the same time to keep away certain insects such as maggots and grubs and is a good remedy for slugs. Air-slaked lime or hydrated lime is the best form to use. FLOWERS OF SULPHUR. — For the control of the red spider and for some other kinds of mites, sulphur may be either dusted on plants or mixed with water, a teaspoonful of sulphur to a quart of water, and sprayed. HOW TO SPRAY To do good work in killing insects and keeping diseases from the plants, spraying must be done in time. Do not wait until the plants ha^•e been harmed beyond help, but begin work as soon as the troul)lc so DEPARTMENT CIRCULAR 35, U. S. DEPARTMENT OF AGRICULTURE is noticed. Use good apparatus and spray carefully, since careless spray- ing merely wastes the mixture. Using a watering pot or whisk-broom is not spraying and will not save the plants. The spray should come from the nozzle in a mist so fine that it floats for some time in the air. This gives a better and finer coat of poison to the leaves and reaches many more insects. Do not use too much of the mixture on the plants. After spraying, the leaves should be wet, but not dripping. If it drips from the leaves, it is being wasted. If a compressed-air sprayer is used, pump it up tight and keep it so. It is better to spray with Bordeaux mixture before a rain, rather than after, if the mixture has time to dry before the rain begins. Dust sticks much better if put on after a rain, or when the dew is on in the morning. A LWAYS clean the sprayer well, inside and out, after using i1 out in a few weeks. ■^^ after using it. Unless this is done it may rust SPRAYING AND DUSTING TOOLS. — The sprays and dusts described may be put on in many ways. For the small garden, an atomizer sprayer (fig. 43) is good, but a compressed-air sprayer is better for gardens of medium size (fig. 44). In the case of the atomizer sprayer, the container for the liquid should be made of glass or brass, as Bordeaux mixture and other materials eat tin and iron. These sprayers cost from 50 to 75 cents. Compressed-air sprayers of galvanized steel may be bought for $3.50 to $5.00, and for $6.50 to $12.50 if made of brass. Dusts may be easily applied by shaking them from a fine cheesecloth bag or from a can with a handle with the bottom perforated with small holes. There are also several cheap dust guns on the market. MISCELLANEOUS CONTROL METHODS SOIL TREATMENT. — Young plants grown in flats or boxes for setting in the garden are often troubled with such diseases as damping-ofl[ (page 5), and clubroot (page 10), which attack the roots and stems of the plants. These troubles live in the soil and the best way to get rid of them is to drench the soil with boiling water a few days before planting the seeds. Set the box of soil over the sink and pour the boiling water into it as fast as the soil will take it up. Use 9 quarts of water for a box 1 foot square with soil 4 inches deep. When the soil has dried out enough, plant the seeds. Seeds in this soil will sprout better and the plants grow faster and stronger than in diseased soil. CARBON DISULPHID. — Carbon disulphid is a clear yellowish liquid with a bad smell. It is used for treating seeds and to kill weevils and other insects which breed in seeds. A tin bucket or can, fitted with an air-tight top, makes a good fumigator. The seed should be placed in the bucket or can and the carbon disulphid poured onto a piece of rag or waste cotton and dropped upon the seed. A teaspoonful of carbon DISEASES AND INSECTS OF THE HOME GARDEN 31 disulphid is sufficient for a l-gallon can or bucket. The lid should then be fitted tightly onto the can or bucket and left on for 2J- hours. The seed should then be removed and aired. r^ARBON DISULPHID is a dangerous explosive when brought near fire. If you wish to fumigate with it, ask your parent or leader to show you how. TRAP CROPS. — Some garden insects which feed on several kinds of plants prefer one kind so much that they will leave the other plants and gather on the favorite. This habit can often be taken advantage of to protect garden crops. For example, a row of radishes may be planted next to cabbages to attract the cabbage maggot. Tomatoes and beans may be protected from the corn earworm by a few hills of early corn near the garden. A crop planted in this way to protect another by attracting the insect pests from it, is called a trap crop. INSECT FRIENDS LADYBIRD BEETLE. — Not all of the insects found on the garden plants damage the crop, as anyone will soon see who closely watches a ladybird beetle (fig. 45) or its peculiar red and bluish young when in a group of plant-lice. Lady- birds, so well known to most gardeners, are among the grow- er's best friends. One of them has been known to eat more than 80 plant lice in a day. Save all of these little red and black helpers that you can. SYRPHUS FLY. — Another friend that feeds on plant-lice is the curious green maggot often found among them. This is the young of a small yellow black-banded fly (fig. 46) that may be found about "lousy" plants. This is known as a syrphus fly and should be pro- tected. There are many other friendly insects, such as ground-beetles, lace- wing flies, and tachina flies. If it were not for these, pests would in- crease so fast that there would soon be no vege- ' ^ -.-O" ^ ^^sm^' ^ -J^ ^A~. \ ) c tables left to feed them. Fig. 45. — A ladybird: o. beetle; 6, pupa; c, young. These beetles and their young eat dozens of plant-lice each day. Fig. 46. — A syrphus fly: a, fly plant-lice. It is about thq ggot. This fly helps keep down of a common house fly. 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