Sweet Potato WeevilThe sweet potato weevil is a serious pest in the field and in storage. Just checked the tomato plants and can’t see anything yet. Several kinds of wireworms feed on sweet potatoes as well as Irish potatoes. Whereas Spintor will control all species of Lepidoptera on the foliage, however, Confirm will provide only fair control of loopers. Sweet potato weevils are most numerous close to the soil surface. Use enough water to wet the plant stems and soil surface. This cutworm remains close to the soil surface and feeds on plant stems and leaves by cutting them off at the ground level. Sweet potato (Ipomoea batatas Lam.) Usually, flea beetle larvae feed on fibrous roots but, when high numbers of beetles are present, they will feed on marketable roots. Adults lay eggs in the soil where larvae emerge in one to two weeks, depending on temperature. Crop rotation can be used effectively to reduce infestation levels. The Shape of the Leaf. Whitefringed beetles over-winter mainly as mature larvae in the soil at a depth of about 9 to 15 inches but can over-winter in the egg stage. Females are parthenogenetic (reproduce without males) and initiate oviposition on the lower plant parts 10 to 12 days after emergence from the pupal stage. Whitefringed beetle larvae are very difficult to control because the larvae often remain deep in the soil where even preplant incorporated soil insecticides may not reach them. I planted the seeds back in the autumn and had hoped I could get them growing using a cold frame idea. The C-shaped grub has a distinct brown head; a shiny, smooth body; and three pairs of legs just behind the head. Foliar applications of insecticides to control cucumber beetles will also control click beetles and June beetles. Repeated cultivation of the fields in the spring will help remove alternate food sources and expose grubs and wireworms to birds and other predators. Females can live for two to five months. Sweet potato leaf curl virus is a begomovirus transmitted by the whitefly species Bemisia tabaci. Because armyworms feed above ground on the plant foliage, they are fairly easy to control; however, the beet armyworm is resistant to pyrethroid insecticides and may have some tolerance to organophosphates as well (Penncap M, Imidan). Adults, known as click beetles, do not feed on the crop but oviposit on the soil near the crop, weeds or other vegetation. Soil insecticides and foliar-applied insecticides will provide protection from flea beetles. Larvae are slightly curved, yellowish-white, legless and have light-brown heads. A bar placed on the spray boom ahead of the nozzles will bend large plants over and let the spray hit the base of the plants. At the end of larval development, larvae drop to the ground, where they burrow into the soil and pupate. Females oviposit on bare soil or soil planted to crops. The adult is oval, black with a bronze tinge and very small. This leaves nearly every weevil egg in the plant bed. Whitefringed beetles can be a serious problem for growers. The life cycle is completed in 30 days in the summer, and there are several generations a year. Early blight (Alternaria solani) For more detailed information on this disease, please see our full … The excretion of honeydew and the subsequent development of sooty mold fungi also may reduce photosynthesis and other physiological functions of the plant. The adult stage is a brown and black moth that is active at night. Adult beetles are black and covered with dark-gray and grayish-brown scales. Because of the long life cycle of white grubs, their presence in the previous season increases the likelihood of injurious numbers in the current season. A preplant soil insecticide (Lorsban) will provide some protection from wireworms and a layby application will extend the residual in the soil. Two species of loopers may occur on sweet potato foliage, the soybean looper and the cabbage looper. Eggs are laid in the roots or stems in holes (one per hole) eaten out by the females. Potato Leaves Nitrogen deficiency Right: nitrogen deficient leaf, pale green and yellow tinted, contrasted with left, normal green leaf with ample nitrogen supply. Insects that injure the foliage reduce the yield of the plants indirectly and are referred to as foliage feeding insects. Control weeds in and around the land. White grubs may be found by turning over (shovel or plow) the soil and checking for grubs in the loose soil. Use at least 15 gallons of water per acre with the insecticide. Contact Information:Telephone: 318-435-2155 Fax: 318-435-2110Postal Address: P.O. New growth becomes stunted and leaves curl downward and pucker. (I live in Orlando, BTW.) Larvae gouge out narrow, shallow to deep channels on the surface of the root. Eliminating weevils from planting material should begin with sanitation in and around the storage area as soon as it is emptied in the spring. Flea beetles are an occasional problem for growers. Sweet potatoes are attacked by a particular species of whitefly pests, aptly named sweetpotato whiteflies (Bemisia tabaci) or silverleaf whiteflies, that look like white bumps on leaves. Early feeding appears as shallow but large cavities. There are bright pink spots on the hind wings and abdomen. Larvae gouge out broad, shallow areas on the root, reducing the marketability of the crop. Start the leaves by growing a sweet potato tuber in water, then detach the rooted slips and place each in a clean jar. Adults emerge from pupae about a week later. They vary from 1/5 to1/3 inch long. Several species of tortoise beetles feed on sweet potato foliage. Pupae are white and are found in the soil at a depth of 3 to 6 inches from late May to the end of July. Injury that occurs closer to harvest will not be healed. Malathion can be sprayed in the storage areas to kill weevils. Early blight, caused by Alternaria solani, is a very common fungal disease present in most regions that produce potatoes.Brown leaf spot (Alternaria alternata) of potatoes has gained attention recently for its similarity to early blight.Just as common, yet underestimated, brown leaf spot presents symptoms that are often incorrectly attributed to early blight. Injury to plants is always more severe under hot, dry conditions. Therefore sweet potatoes and intact crowns should not be left in the field after harvest. The eggs are white, oval to spherical and very small. They are called tortoise beetles because they resemble tortoises. Several species of armyworms feed on sweet potato foliage, including the southern armyworm, yellow-striped armyworm and beet armyworm. Normally you don’t see them at all, but you can see them when swollen (see photo above). Larvae also tunnel through the vine next to the soil. The soybean looper has shown resistance to pyrethroids but will be controlled by Spintor or the organophosphates (Imidan, Penncap M), the carbamates (Sevin) or the Bts. Place three pheromone traps about equal distance apart per 40-acre field. Control of cutworms can be achieved with many insecticides including Sevin. 156. Following egg lay, the holes are covered by a grayish mass that hardens to form protective caps over developing eggs. Planting sweet potatoes into these areas will also increase the likelihood of these pests. Defoliation late in the season will have less of an impact on yield than defoliation in the earlier stages. Roots injured during early development will have many unsightly healed holes at harvest. Whitefringe beetle larvae chew comparatively narrow and irregular ‘channels’ on the surface of the root. Mature caterpillars reach a length of 3 ½ inches. Sweet potato virus 2 is also referred to as sweet potato virus Y or sweet potato vein mosaic virus. Eggs are oval to spherical and dull pearly white when first deposited, turning dark just before larval emergence. What is potato early blight? My other container of first earlies were fine but they were harvested before this weeks rain. With higher numbers of the beetle, reduce the spray interval to five days. Chemical control of aphids, however, has little effect due to the rapid nature of transmission. But if all the practices are used together, they assure that the plants taken to the field will be as weevil free as possible. Anthracnose ... white Albugo ipomoeae-panduratae: Scab, leaf and stem Sphaceloma batatas. White grubs gouge broad, shallow to deep, irregular areas on the surface of the root. When fully grown, wireworms range from 1/2 to 1 inch in length. During this time these adults may lay eggs in sweet potato fields. The cabbage looper is susceptible to all the insecticides. Thrips are spindle-shaped and 1/16 inch or less in length. Eggs are laid singly on the lower surface of leaves. web@agcenter.lsu.edu, 106 Martin D. Woodin Hall They are the opposite end of the garden. Adults mate soon after emergence from the root but egg laying does not occur for four to seven days. The adult moth is heavy-bodied and gray with a wingspan of about 4 inches. These armyworms have a broad host range, feeding on many plants including several vegetable and field crops as well as weeds. Both species feed on several different host plants including vegetable and field crops, as well as weeds. Thrips rasp the tender parts of center leaves and/or terminal buds with their sharp mouthparts and feed on escaping juices. This provides healthy mother stock plants, enabling vine growers to start each season with planting material of disease-tested origin. Devining at harvest helps to destroy crowns. Adult white grubs (May beetles, June beetles) are generally active in the spring and early summer. Avoid planting potatoes in extremely wet conditions with poor drainage. The front wings are wide, and the first hardened plate of the thorax covers the head. The head and legs are covered in a roof-like manner by the margins of the body. There are from three to five generations per year, depending on the species. The feeding by the larvae (worm stage) can be troublesome under dry conditions late in the season where there is a lot of soil cracking. Adults are white insects (up to 3/32 inch) that resemble tiny moths. A preplant soil insecticide (Mocap, Lorsban) will provide some protection for these pests in the same way it will control rootworms and wireworms. Ideally, beds should also be far away from the new fields (at least 1 mile). The southern potato wireworm (Conoderus falli) is injurious in the southeastern United States.Adults (click beetles) are dark brown, about ¼-inch long and are found near the soil surface under leaves and trash in sweet potato … Adult flea beetles are active during the day and can be captured in sweep nets. By Dr Julia Mulabisana and Dr Sunette Laurie, © 2020 Farmer's Weekly Magazine | Caxton Magazines Digital |, Identifying and controlling sweet potato viruses, Canola: the crop that requires perfect planning, SA avocado exports to European market under pressure, Top score for SA Wagyu x Angus carcass on Japanese scale, World’s largest pig farm aims to produce 2 million hogs a year, Essential oils: a balm for emerging farmers, Expropriation bill “risks credit flight, downgrades” for SA. Seeing your potato leaves turning black will really scare you quite a bit; especially if your plants looked perfectly fine and healthy yesterday! Healthy planting material can yield between 20t/ ha and 25t/ ha, while material infected with multiple virus infections can have a yield as low as 1t/ha to 4t/ha. Larvae found in the vine usually come from eggs deposited in the plant production bed. Cucumber beetles are oblong-oval, have beaded antennae and are about ¼ inch long. The presence of an infestation the previous year then indicates close attention is warranted in the current year. The vines need no other food, just an occasional water change. The adults and nymphs of these soft-bodied, pear-shaped insects are usually pale to dark green but sometimes yellow. Potato Scab The larvae have fat, legless, C-shaped bodies that are dirty white with a pale brown head. Some of the more important ones in South Africa are described below. The plants usually wilt and die. These beetles can be sampled with a vacuum sampling device, they can be searched for by hand or their presence can be detected by the presence of notched leaves. Whitefringed beetles cannot fly, so they move very little from year to year. Sweet potatoes and crowns left in the field after harvest may provide a haven for the weevil in winter, especially when sweet potatoes are covered by soil. These aren’t yet another problem thank goodness, but lenticels. They have a pale yellow to reddish-brown body and a brown, flattened head. Much to my surprise as soon as the soil warmed up this spring plants popped up. If your potato plants start to exhibit small, irregular dark brown spots on the lowest or oldest leaves, they may be afflicted with early blight of potatoes. Larvae will chew on exposed sweet potato roots. Place beds as far away as possible from last year’s sweet potato fields. Damage – Damage occurs as ragged holes in the roots. Over-wintering occurs in protected places such as under logs or leaves, along fencerows and at the edges of wooded areas. Potato Leaves Yellow Spots. The grub will tunnel through leaves and roots. They flutter when disturbed. Larva of sweet potato weevil is a white, legless grub with a pale brown head about 3/8 inches long; the adult beetle has a reddish snout. Tubers may be rotten upon harvest or rot in storage later on. These baits should be buried in the soil about 3 to 4 inches deep and left for seven to 10 days. The sweet potato flea beetle feeds on several plants including sweet potato, morning glory and bindweed. The onion thrips is dark brown. Lenticels are minute organs used by the tuber to breathe but in waterlogged soils they become blocked and swell up. It is the most serious disease affecting sweet potato in East and West Africa, and has also been reported in isolated areas in Southern Africa. Good coverage is essential for control. Adult beetles can be monitored with sweep nets. Potato plants often have spots on the leaves, and the causes vary from serious diseases to something harmless. Although single infections occur occasionally, the viruses are detected mostly in crops already infected with other viruses. Apply it with a recirculating duster for good coverage. The adult of the sweet potato weevil is a snout beetle that looks antlike. The eggs are very small, oblong-oval and white. They emerge in late May through mid July. They are about 1/2 inch long. Other control measures include the following: The science behind the virus detection Depending on environmental conditions, the insecticide used and the coverage obtained with the spray application, a foliar-applied insecticide may kill beetles for anywhere from one day to one week. The adult feeds on the root, puncturing numerous small holes and laying eggs in these punctures. Does this plant require special care as a houseplant? Alternaria leaf spot and stem blight Alternaria spp. Larvae of these two species are very difficult to tell apart. 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