The use of a high rate of gallonage and high pressure will help penetrate the foliage to get the insecticide to the soil surface level where the cutworms occur. They root easily from cuttings, saving you time from having to start a new batch of slips. Sweet potato chlorotic stunt virus is a crinivirus transmitted by the whitefly species B. tabaci. Eggs are laid in the soil near plants in the spring when adults emerge from over-wintering sites. Does this plant require special care as a houseplant? Sweet potato weevils are most numerous close to the soil surface. Foundation or certified seed free of weevils should be used. Cucumber beetles are oblong-oval, have beaded antennae and are about ¼ inch long. Adults mate soon after emergence from the root but egg laying does not occur for four to seven days. https://www.ehow.com/info_12173842_white-spots-sweet-potatoes.html Potato plants often have spots on the leaves, and the causes vary from serious diseases to something harmless. The eggs are white, oval to spherical and very small. Larvae emerge from eggs in a few days, feed for about three weeks and pupate in the soil. There are two to three generations per year, with the pupa being the over-wintering stage. Click beetles tend to be active at night and will not be captured with a sweep net during the day. Whitefringe beetle larvae chew comparatively narrow and irregular ‘channels’ on the surface of the root. Eggs are laid in the roots or stems in holes (one per hole) eaten out by the females. 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. What you’re actually seeing when you notice white droplets leaking from your sliced sweet potato is the sap from the sweet potato plant. Individual practices recommended to produce weevil-free plants will not be completely effective if used alone. 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. Adults are white insects (up to 3/32 inch) that resemble tiny moths. The banded cucumber beetle is the most common cucumber beetle attacking sweet potatoes in Louisiana, but the spotted cucumber beetle will also feed on sweet potatoes. They emerge in late May through mid July. This will control the weevils that survived the winter in the previous year’s fields. At the end of larval development, larvae drop to the ground, where they burrow into the soil and pupate. Injury to plants is always more severe under hot, dry conditions. These injured areas will turn brown and die. Sweet Potato WeevilThe sweet potato weevil is a serious pest in the field and in storage. The adults chew shallow narrow channels or grooves in the upper surface of leaves. With higher numbers of the beetle, reduce the spray interval to five days. Under such conditions the granulate cutworm may crawl into the soil cracks and feed directly on the developing root, chewing a circular hole that may be ¼ to ½ inch deep. One contained white potatoes and the other sweet potatoes. 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. 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. Other species of flea beetles such as the pale-striped flea beetle may be found in sweet potato fields. Adult moths emerge to start a new generation. These beetles are oblong-oval and slightly flattened. Use enough water to wet the plant stems and soil surface. Larvae, or caterpillars, emerge from eggs in four to six days and spend three to four weeks as larvae feeding on the plant. Normally you don’t see them at all, but you can see them when swollen (see photo above). Potatoes Small White Spots – Lenticels The reds (can’t remember the variety offhand) are reasonable but covered in small white spots. The potato tubers grow underground and generally located in the top 25 cm (10 in) of the soil. Remove and destroy infested plants. Because this species has several generations per year, a wide host range and is very mobile as adults, it is one of the most difficult soil insect pests to control. 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. Chemical control of aphids, however, has little effect due to the rapid nature of transmission. Adults prefer to feed on the older plant foliage, but consume little. Larvae produce small, round shallow feeding holes on the root surface. Several species of white grubs are pests of sweet potatoes, but the most prevalent species is Phyllophaga ephilida. 'Margarita' is its favorite. Two species of loopers may occur on sweet potato foliage, the soybean looper and the cabbage looper. During this time click beetles may lay eggs in sweet potato fields. Much to my surprise as soon as the soil warmed up this spring plants popped up. These armyworms have a broad host range, feeding on many plants including several vegetable and field crops as well as weeds. The sweet potato plant is a branching, creeeping vine with spirally arranged lobed, heart shaped leaves and white or lavender flowers. Lenticels are minute organs used by the tuber to breathe but in waterlogged soils … 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. Box 120Chase, LA 71324e-mail: tsmith@agcenter.lsu.edu, The LSU AgCenter and the LSU College of Agriculture, 101 Efferson Hall I ended up cutting 1" wedges, and washed the white stuff off, and nuked them and tasted fine. 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. The onion thrips is dark brown. These new larvae will not be killed once the soil insecticide has broken down. These aren’t yet another problem thank goodness, but lenticels. This reduces the likelihood of any surviving weevils finding the beds. I’ll be harvesting the potatoes in a couple of days and roast, then freeze. The potato plant produces white or blue flowers and yellow-green berries. Potato Leaves Yellow Spots. Decayed spots may be dry or soft, the latter due principally to Rhizopus rot. Insects that injure the foliage reduce the yield of the plants indirectly and are referred to as foliage feeding insects. The injury from the weevil is from adults and larvae. There are bright pink spots on the hind wings and abdomen. Adults are reddish-brown to black and elongate. Injury that occurs closer to harvest will not be healed. In North Louisiana, the spotted cucumber beetle predominates. Spray preventatively to limit the spread of the virus. The three viruses can be found infecting a single sweet potato plant and have been observed in Limpopo, Mpumalanga and Gauteng. 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. There are multiple generations per year. New growth becomes stunted and leaves curl downward and pucker. The samples may then be dug and checked by washing through a sieve. Leaf symptoms vary with cultivar, climatic conditions and plant age. Repeated cultivation of the fields in the spring will help remove alternate food sources and expose the larvae to birds and other predators. Adults emerge from pupae about a week later. The Shape of the Leaf. za, or Dr Sunette Laurie at [email protected]. Just checked the tomato plants and can’t see anything yet. Email Dr Julia Mulabisana at [email protected] agric. Several species of tortoise beetles feed on sweet potato foliage. They have two longitudinal stripes and a marginal band of white hairs. 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. Foliar insecticide applications for the soil insect pests will control the defoliating insects. As with cucumber beetles and white grubs, wireworms may be present in the field as larvae before planting. I cut into this sweet potato and a few seconds later, these crazy white spots appeared. First the potatoes and a few weeks later the sweet potatoes. All stages of the weevil can be found in the root. 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). 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. The tubers can be variable in shape and can be red, yellow, brown, white or purple in color. The pupal period lasts three weeks in the summer, then adults emerge to start a new generation. Potato Blackleg Common during wet growing seasons, potato blackleg causes leaves to turn pale green or yellow. Spintor and Confirm are effective against the beet armyworm. 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 virus 2 symptoms are generally chlorotic spots with diffuse mottling on the leaves (see Figure 2A). To control this pest, plant a different selection or spray your plants according to label directions with neem oil or spinosad. The sweet potato weevil larva is the only insect that tunnels throughout the root. Wireworms can be sampled in the spring using corn or small potatoes as baits before planting. Potato Leaves Spots. 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. 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. A preplant soil insecticide (Mocap, Lorsban) will provide some protection for these pests in the same way it will control rootworms and wireworms. This is the handiwork of the sneaky golden tortoise beetle. They are daytime feeders but are sometimes difficult to find because they move to the base of the plant. Potatoes should be stored at 55oF to 60oF, and at 85% – 90% relative humidity. Larvae feed on the foliage for about three weeks and then they burrow into the soil where they pupate. Potato flea beetle damage on potato foliage appears as scallop-like scoops, rounded pits or shotholes originating from the underside of the potato leaf. 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 … Larvae found in the vine usually come from eggs deposited in the plant production bed. Sweet potatoes infested with weevils are not only unsightly, but they taste bitter. Admire is the most effective insecticide for controlling whiteflies. Pick off weevils. What is Potato … I cut another wedge off and the same thing happened. Let’s dig a little deeper… Wireworms have a very broad host range and will feed on weeds in the fields. The Guide to Sweet Potato Production in South Africa can be purchased from the ARC-VOP by emailing Tsholofelo Tselapedi at [email protected]. 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. Usually, flea beetle larvae feed on fibrous roots but, when high numbers of beetles are present, they will feed on marketable roots. 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. Pull off any lower leaves, leaving only one or two at the top. Sweet potato hornworm moths are present from June to September. Females can live for two to five months. Wilting and discoloration follow. Cucumber beetle eggs are orange-yellow and oval and found in clusters in the soil at the base of plants. Sweet potato (Ipomoea batatas Lam.) Alternaria storage rot Alternaria spp. They are often found on the undersides of leaves and are often associated with honeydew and sooty molds. Larvae feed on roots, leaving shallow, narrow winding tunnels. The grub will tunnel through leaves and roots. Adult flea beetles are active during the day and can be captured in sweep nets. Many insects feed on the foliage. It didn’t work. They vary from 1/5 to1/3 inch long. You can harvest leaves at any time or harvest the entire vine. Flea beetles are an occasional problem for growers. Admire is the most effective insecticide for controlling aphids. Good coverage is essential for control. There are several generations a year. They flutter when disturbed. Adult beetles are black and covered with dark-gray and grayish-brown scales. WirewormsSeveral species of wireworms seriously injure sweet potatoes. The adult moth is heavy-bodied and gray with a wingspan of about 4 inches. I’m starting to freak out a bit because the other day I noticed that I had a few yellow leaves – I pulled them off and didn’t worry. Read on to learn how to identify potatoes with early blight and about potato early blight treatment. Growth tends to be squat and bushy; leaflets bluish green and slight intervenal chlorosis, marginal scorch and brown spots on under surface. Planting sweet potatoes into these areas will also increase the likelihood of these pests. Feeding holes are in groups and may enlarge as roots develop. The banded cucumber beetle is the most common rootworm that injures sweet potato roots in Central Louisiana. Foliar applications of insecticides to control cucumber beetles will control click beetles. Wireworms have a longer life cycle than cucumber beetles and as adults are less mobile. Two banded cucumber beetles per 100 sweeps indicate the need to spray on a seven-day interval. Use at least 15 gallons of water per acre with the insecticide. Place beds as far away as possible from last year’s sweet potato fields. Adults, known as May beetles or June beetles, are shiny reddish-brown to black and are 1/2 to 1 inch long. The adults and nymphs of these soft-bodied, pear-shaped insects are usually pale to dark green but sometimes yellow. The first segment of the hind pair of legs is greatly enlarged and allows flea beetles to jump like fleas. The plant has enlarged roots called tubers which act as an energy store for the plant. What is potato early blight? Sweet potato feathery mottle virus and sweet potato virus C are transmitted by the aphid species Myzus persicae and Aphis gossypii. Baton Rouge, LA 70803 Fully grown cucumber beetle larvae are 1/4 to 1/3 inch long. If I moved my finger across the spots, they absorbed back into the sweet potato. The sweet potato whitefly is the most common species of whitefly on sweet potato. 225-578-4143 This leaves nearly every weevil egg in the plant bed. Alternaria leaf spot and stem blight Alternaria spp. White grubs are often found in large numbers in pastures and grassy areas. Finally, monitor activity in the field. The vines need no other food, just an occasional water change. Foliar applications of insecticides to control cucumber beetles will also control click beetles and June beetles. Eliminating weevils from planting material should begin with sanitation in and around the storage area as soon as it is emptied in the spring. I planted the seeds back in the autumn and had hoped I could get them growing using a cold frame idea. Larvae feed on leaves, tender stems and branch tips. Eggs are placed in masses on the foliage by moths. During this time these adults may lay eggs in sweet potato fields. The larvae have fat, legless, C-shaped bodies that are dirty white with a pale brown head. Impact of sweet potato viruses on yield They are actually swollen lenticels caused by too much water. A study conducted at the ARC’s Vegetable and Ornamental Plants (ARC-VOP) division to determine the impact of single, co- and mixed virus infections on the yield of sweet potato varieties, revealed that graft-inoculated plants with a mixed infection of sweet potato feathery mottle virus, and begomoviruses such as sweet potato leaf curl São Paulo virus and sweet potato mosaic virus reduced yield by an average of 68% in the first season of planting (see Graph 1). Thrips rasp the tender parts of center leaves and/or terminal buds with their sharp mouthparts and feed on escaping juices. 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. Although single infections occur occasionally, the viruses are detected mostly in crops already infected with other viruses. as nitrocellulose enzyme-linked immunosorbent assay (NCM-ELISA) and double antibody sandwich ELISA (DAS-ELISA), using a broad spectrum antiserum. Control weeds in and around the land. This provides healthy mother stock plants, enabling vine growers to start each season with planting material of disease-tested origin. These insects chew small, shallow circular or oblong holes through the skin of the root. • Holes in leaves and roots. The adults will feed above ground and can be controlled with foliar applications of insecticides (Penncap or Imidan). The head and legs are covered in a roof-like manner by the margins of the body. Eggs are white or pale yellow, broadly oval and are very tiny. Such tunnels will split open, leaving shallow, dark scars. The adult is about ¼ inch long. The spherical egg is translucent with a greenish tint. Prevention and control Other soil insects feed on the surface of the developing root. Sweet potato virus 2 is also referred to as sweet potato virus Y or sweet potato vein mosaic virus. As lesions expand, they can girdle ste… 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. The wing covers have deep ridges and the legs are reddish-yellow. Because of the long life cycle of wireworms, the presence of these insects in the previous season increases the likelihood of injurious numbers in the current season. They are often found on the undersides of leaves and are often associated with honeydew and sooty molds. Farmers are strongly discouraged from reusing sweet potato planting material. Let’s take a look at what different types of spots on potato leaves mean. Insects that damage the roots directly are the most troublesome and are referred to as soil insect pests. Pupation occurs within the sweet potato, and this stage lasts for five to 11 days. At this point, if adults exceed threshold levels, resort to foliar applications to prevent rootworm injury. Larvae over-winter in the soil. Good insecticide coverage of all the sweet potatoes in a pallet box or James crate is necessary. Adults over-winter under bark or in leaf litter. Pupae are found in cells just below the soil surface, and adults emerge in about one week. The life cycle varies from species with two generations per year to species with life cycles lasting two to three years. Repeated cultivation of the fields in the spring will help remove alternate food sources and expose wireworms to birds and other predators. Adult thrips have pairs of long, narrow wings fringed with long hairs. Also, it helps reduce the spread of numerous diseases and root-knot nematodes. Tortoise beetles are brightly colored, usually gold with black and/or red markings, depending on the species. 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