Armyworm larvae are often found on foliage during the morning, evening or during the day if it is cloudy. During this time click beetles may lay eggs in sweet potato fields. The onion thrips is dark brown. Box 120Chase, LA 71324e-mail: tsmith@agcenter.lsu.edu, The LSU AgCenter and the LSU College of Agriculture, 101 Efferson Hall Place beds as far away as possible from last year’s sweet potato fields. These insects can cause economic loss, but usually only at very high numbers, and it is relatively easy to control them with insecticides because they are exposed on the plant. These baits should be buried in the soil about 3 to 4 inches deep and left for seven to 10 days. 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. Larvae produce small, round shallow feeding holes on the root surface. There are bright pink spots on the hind wings and abdomen. Flea beetles chew shallow, narrow, winding tunnels along the surface of the root. Eggs are placed in masses on the foliage by moths. Finally, monitor activity in the field. Whitefringed beetles can be a serious problem for growers. Honeydew secreted by aphids makes plants sticky and enhances development of black sooty mold on plant foliage. This will control the weevils that survived the winter in the previous year’s fields. Depending on environmental conditions, incubation of eggs varies from four to 56 days. There are several generations a year. Email Dr Julia Mulabisana at [email protected] agric. Two banded cucumber beetles per 100 sweeps indicate the need to spray on a seven-day interval. Host Plants – The tobacco wireworm apparently prefers tobacco, but it feeds on a variety of other plants including cotton, corn, potatoes, sweet potatoes, and various truck crops. Remove volunteer sweet potato plants that may have survived from previous crops. 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. Wireworms have a longer life cycle than cucumber beetles and as adults are less mobile. Wireworms. White grubs have a longer life cycle than cucumber beetles. I ended up cutting 1" wedges, and washed the white stuff off, and nuked them and tasted fine. This leaves nearly every weevil egg in the plant bed. The adults and nymphs of these soft-bodied, pear-shaped insects are usually pale to dark green but sometimes yellow. Sweet potatoes can be grown as a second crop if your warm season is long enough. Use at least 15 gallons of water per acre with the insecticide. Adults emerge from pupae about a week later. Alternaria leaf spot and stem blight Alternaria spp. Also, it helps reduce the spread of numerous diseases and root-knot nematodes. The stem remains strong, but more leaves begin to wilt and eventually turn yellow. Adults are white insects (up to 3/32 inch) that resemble tiny moths. Aphids tend to spread rapidly from field to field, transmitting a number of viral diseases. The body is cylindrical and slender, reaching a length of 1/5 inch. Good coverage is essential for control. and at 90 percent relative humidity before being stored. These injured areas will turn brown and die. Larvae are often abundant in pasture, sod or weedy fields and can injure roots severely when sweet potatoes are planted in fields that follow pasture. Larvae, or caterpillars, emerge from eggs in four to six days and spend three to four weeks as larvae feeding on the plant. The adult of the sweet potato weevil is a snout beetle that looks antlike. Melon aphid is a primary vector of sweet potato feathery mottle virus. The larvae emerge from eggs in two weeks to three months, depending on temperature. The adults become active in the spring and feed on weed hosts until sweet potatoes are available. What you’re actually seeing when you notice white droplets leaking from your sliced sweet potato is the sap from the sweet potato plant. What is Potato … The ARC-VOP has kept the sweet potato industry profitable over many years by running a disease-tested scheme. Loopers can be distinguished form armyworms by the ‘looping’ motion when they crawl: they arch their back up while moving in a forward direction because of a reduced number of legs on the abdomen. Adult flea beetles are active during the day and can be captured in sweep nets. Answered. Larvae found in the vine usually come from eggs deposited in the plant production bed. Potato Leaves Yellow Spots. 'Margarita' is its favorite. However, comparison of the coat protein amino acid sequences revealed that it is distinct from other strains of sweet potato feathery mottle virus. 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. Spray the beds weekly with Imidan, Sevin, Thiodan or Penncap M. Start spraying as soon as the plastic mulch is pulled off, and continue weekly applications until the last cutting of plants. June beetles tend to be active at night and will not be captured with a sweep net during the day. Larvae are slightly curved, yellowish-white, legless and have light-brown heads. Contact Information:Telephone: 318-435-2155 Fax: 318-435-2110Postal Address: P.O. Newly emerged adults wait one to three days before leaving the root. The head and abdomen are metallic dark blue, and the thorax and legs are red. The original holes are usually less than 1/4 inch deep, but may be considerably deepened by later growth of the sweet potato root. I’ve just sprayed my tomato plants … The reason for spraying the base of the plants and the soil surface is that the female weevils stay on the soil surface of just above or below it, and almost all the eggs are placed within an inch of the soil surface. 155. Cucumber beetles are oblong-oval, have beaded antennae and are about ¼ inch long. Having your own potato patch ensures an ongoing supply of buttery baked or mashed potatoes, crispy hash browns, refreshing potato salad or a host of other satisfying dishes. Heavily infested plants turn brown and die from the top down. I cut another wedge off and the same thing happened. These become quickly covered with a white cottony growth that can spread rapidly to nearby stems and leaves if moisture is present for several hours. They are daytime feeders but are sometimes difficult to find because they move to the base of the plant. They root easily from cuttings, saving you time from having to start a new batch of slips. Virus-infected sweet potato vines used as planting material act as sources of infection and can transmit viruses from one place to another. 225-578-4161 Tubers may be rotten upon harvest or rot in storage later on. Lesions usually first appear in the intersections between the stem and branches, or on branches and stems in contact with the soil (Photo 2). There are from three to five generations per year, depending on the species. 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. Growth tends to be squat and bushy; leaflets bluish green and slight intervenal chlorosis, marginal scorch and brown spots on under surface. Spray preventatively to limit the spread of the virus. Several kinds of wireworms feed on sweet potatoes as well as Irish potatoes. You can harvest leaves at any time or harvest the entire vine. Read on to learn how to identify potatoes with early blight and about potato early blight treatment. They are called tortoise beetles because they resemble tortoises. They have a pale yellow to reddish-brown body and a brown, flattened head. At the end of larval development, larvae drop to the ground, where they burrow into the soil and pupate. Cutting or slicing traumatizes the cells of the sweet potato and causes the sap to come out of the cells onto the surface. The cabbage looper is susceptible to all the insecticides. Sweet potatoes are an important commercial crop and contribute significantly to food security in many poorer South African households. White mold symptoms first appear as water-soaked lesions 14 to 20 days following row closure, depending on the cultivar and cultural practices (see white arrows on Photo 1). The adult is oval, black with a bronze tinge and very small. Fully grown cucumber beetle larvae are 1/4 to 1/3 inch long. Pull off any lower leaves, leaving only one or two at the top. The adults will feed above ground and can be controlled with foliar applications of insecticides (Penncap or Imidan). Sprinkle plants with diatomaceous earth. There are several generations per year. “Hey David! This is the handiwork of the sneaky golden tortoise beetle. Once cutworms crawl into soil cracks, control will be difficult. An aphid can acquire the virus from infected plants in less than a minute while feeding, and transmit it to a healthy plant in seconds. As a general rule, defoliation must exceed 30 percent before yields are reduced. This provides healthy mother stock plants, enabling vine growers to start each season with planting material of disease-tested origin. As lesions expand, they can girdle ste… Therefore sweet potatoes and intact crowns should not be left in the field after harvest. Does this plant require special care as a houseplant? Larvae feed on roots, leaving shallow, narrow winding tunnels. Click beetles tend to be active at night and will not be captured with a sweep net during the day. Much to my surprise as soon as the soil warmed up this spring plants popped up. I planted the seeds back in the autumn and had hoped I could get them growing using a cold frame idea. Sweet potato virus 2 is also referred to as sweet potato virus Y or sweet potato vein mosaic virus. Even low numbers of larvae reduce sweet potato quality and marketable yield. Roots injured during early development will have many unsightly healed holes at harvest. Both adults and larvae can be found on the leaves. A preplant soil insecticide (Mocap, Lorsban) will provide some protection for these pests in the same way it will control rootworms and wireworms. They are often found on the undersides of leaves and are often associated with honeydew and sooty molds. A preplant soil insecticide (Lorsban) will provide some protection from wireworms and a layby application will extend the residual in the soil. Cucumber beetle larvae, called rootworms, have a yellow-white, somewhat wrinkled body with three pairs of brownish legs near the head and a single pair of prolegs near the tip of the abdomen. This insect will also feed on morning glory. Fortunately, these are physiological problems and not caused by disease or insects. Over-wintering occurs in protected places such as under logs or leaves, along fencerows and at the edges of wooded areas. Whitefringe beetle larvae chew comparatively narrow and irregular ‘channels’ on the surface of the root. 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. Instead, they should obtain cuttings from vine growers who replace their stock annually with virus-indexed planting materials obtained from the ARC-VOP. They vary from 1/5 to1/3 inch long. Eliminating weevils from planting material should begin with sanitation in and around the storage area as soon as it is emptied in the spring. Eggs are laid singly on the lower surface of leaves. Prevention and control Small blister–like bumps on the leaves of ivy geraniums, sweet potato vines, tomatoes and other plants growing indoors or in greenhouses are symptoms of oedema (edema) and intumesence. The adult banded cucumber beetle is marked with alternating green and yellow bands, and the spotted cucumber beetle has a bright yellowish-green body with 12 black spots and a black head. The head and legs are covered in a roof-like manner by the margins of the body. There are two to three generations per year, with the pupa being the over-wintering stage. The injury caused by rootworms and wireworms is similar and cannot be separated easily. These armyworms have a broad host range, feeding on many plants including several vegetable and field crops as well as weeds. Many insect pests have the potential to reduce the quality and yield of sweet potatoes. They can cause economic loss in relatively low numbers, and it is difficult to control them with insecticides because they live below the soil surface. When sweet potatoes are harvested under good conditions with a digger, all of the crop debris will be on top of the soil where it will decompose in winter. The field should not be plowed until late winter or spring because rots covered by soil provide a good over-wintering place for the weevil. I’ll be harvesting the potatoes in a couple of days and roast, then freeze. This reduces the likelihood of any surviving weevils finding the beds. The head is green or brown with three stripes on each side. Answer. Control of cutworms can be achieved with many insecticides including Sevin. The presence of an infestation the previous year then indicates close attention is warranted in the current year. Weevils may also survive the winter in stored seed. The pupa is reddish-brown and is found in the soil. The eggs are white, oval to spherical and very small. The life cycle from oviposition to adult emergence requires about five weeks in the summer. Reductions in yield by 58% and 52% on average were recorded when varieties were inoculated with a single infection of sweet potato feathery mottle virus, and a co-infection of sweet potato leaf curl São Paulo virus and sweet potato mosaic virus, respectively, in the first season of planting. Sweet Potato WeevilThe sweet potato weevil is a serious pest in the field and in storage. The plant has enlarged roots called tubers which act as an energy store for the plant. I have 2 raised beds. Spintor and Confirm are effective against the beet armyworm. Let’s dig a little deeper… Larvae will chew on exposed sweet potato roots. If a single trap catches as many as four weevils in a week, begin weekly foliar spray applications (Imidan, Penncap M, Sevin, Thiodan) until weevil numbers drop to below the threshold level. Chemical control of aphids, however, has little effect due to the rapid nature of transmission. Larvae feed on the foliage for about three weeks and then they burrow into the soil where they pupate. Injury to plants is always more severe under hot, dry conditions. The Shape of the Leaf. The sweet potato weevil larva is the only insect that tunnels throughout the root. Repeated cultivation of the fields in the spring will help remove alternate food sources and expose grubs and wireworms to birds and other predators. Many insects feed on the foliage. The long antennae are reddish-brown, with the last segment forming a thick club. Direct damage is caused by the removal of sap, and indirect damage as a disease vector. At this point, if adults exceed threshold levels, resort to foliar applications to prevent rootworm injury. A wireworm larva is cylindrical with three pairs of short legs near its head. Larvae are green to brown with slanted black lines on both sides of the body and a black anal horn. Several species of tortoise beetles feed on sweet potato foliage. Sweet potato vine: leaves start turning brown and dying! Symptoms induced by a combination of sweet potato feathery mottle virus, sweet potato virus 2 and sweet potato virus G are more severe than in the case of a single infection. Whitefringed beetles have been reported on more than 385 plant species, including peanuts, corn, sugarcane, cotton, cowpea, beans, cole crops, alfalfa and sweet potatoes. Eggs are deposited near the soil surface on objects such as plant stems and debris lying on or protruding from the soil, but they can also be deposited in the soil at depths of 1 to 4 inches. Nucleic acid-based molecular techniques such as reverse transcription polymerase chain reaction (RT-PCR) and PCR are also used as rapid detection tests for the most common viruses of sweet potato. These beetles are oblong-oval and slightly flattened. One of those phenols, called chlorogenic acid, is the culprit that makes sweet potatoes -- and sometimes, regular potatoes -- darken when they're cooked. The most common problem people experience with sweet potato vines is discovering leaves riddled with holes. The length of the life cycle varies; some species complete a generation in one year, and others require two to three years to complete a generation. I would see moisture, and perhaps burrowers, as the only constraints on a method like this. Admire is the most effective insecticide for controlling whiteflies. Alternaria storage rot Alternaria spp. Oftentimes a single root may have 10 or more small holes. Farmers are strongly discouraged from reusing sweet potato planting material. Adult wireworms (click beetles) are generally active in the spring and summer. Larvae of these two species are very difficult to tell apart. Potato Leaves Spots. The pupal period lasts three weeks in the summer, then adults emerge to start a new generation. Potato flea beetle damage on potato foliage appears as scallop-like scoops, rounded pits or shotholes originating from the underside of the potato leaf. Focus particularly on wild Ipomoea species, as these harbour viruses when sweet potato is not in season. Every time my plant looks like it's doing great, the leaves start turning brown and dying. Baton Rouge, LA 70803, Sweet Potato Insect Pest Management (IPM). This spraying will also take care of an occasional infested seed that did not get enough Imidan dust to kill weevils. I am a new gardener (new to veggies, anyway) – and I grew my own slips from an organic sweet potato from Publix, planted them in early June, and have been gleefully watching them grow. After the last cutting of plants, destroy the beds. The potato tubers grow underground and generally located in the top 25 cm (10 in) of the soil. WirewormsSeveral species of wireworms seriously injure sweet potatoes. Adults, known as click beetles, do not feed on the crop but oviposit on the soil near the crop, weeds or other vegetation. Sweet potato (Ipomoea batatas Lam.) As with cucumber beetles and wireworms, white grubs may be in the field before planting. Whereas Spintor will control all species of Lepidoptera on the foliage, however, Confirm will provide only fair control of loopers. Crop rotation can be used effectively to reduce infestation levels. Larvae gouge out narrow, shallow to deep channels on the surface of the root. A threshold of five beetles per 100 sweeps is recommended before applying insecticides. They have two longitudinal stripes and a marginal band of white hairs. Appear at the base of the virus spintor will control the defoliating insects larvae, rootworms., irregular areas on the variety, oblong-oval and white on weed hosts until sweet potatoes extremely. 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