72 articles tagged "Insect and Mite Management".

Figure 3. Webbing produced on heavily infested cucumber leaves by two-spotted spider mite.

Despite the wet start to the summer that we are experiencing, we have some growers reporting spider mites in field watermelons (Figure 1). This pest is typically associated with hot, dry weather and can be especially problematic in crops grown under protection, such as in high tunnels. Spider mites often move into a field from an adjacent fencerow or rye strip. Two-spotted spider mites (Figure 2.) are most commonly a problem on watermelon and cucumbers in high tunnels, but also affect muskmelons. They can be detected by observing the yellowish discoloration on the upper side of the leaves or using a 10x hand lens and scouting on the underside of the leaf for the pest. Alternatively, you may use a white sheet of paper and tap the leaves above the paper to dislodge the mites; you will see them moving about on the sheet of paper. Because mites often migrate[Read More…]


Figure 1. A cucumber plant grown in a high tunnel died because of bacterial wilt.

Bacterial wilt is one of the most destructive diseases in high tunnel cucumber production. The reason bacterial wilt is so important is because, like other wilt diseases, it ties up with the entire vascular system of a plant, causing systemic effects (Figure 1). The relatively less important roles that other cucumber diseases play also make bacterial wilt the major limitation for high tunnel cucumber production in Indiana. For example, common cucumber diseases such as angular leaf spot, anthracnose and Alternaria leaf blight seldom occur in a high tunnel scenario; improved resistance to powdery mildew was observed in some of the newly developed cucumber varieties; downy mildew in general does not occur in Indiana until end of the high tunnel cucumber production season. The causal organism for bacterial wilt of cucumbers is Erwinia tracheiphila. After the bacteria enter the plant vascular system, it multiplies quickly. As a result, it interferes with[Read More…]


Figure 1. Seedcorn maggot in a melon stem

Three species of seed and root maggots attack vegetables in Indiana. The seedcorn maggot feeds on seeds and seedlings of sweet corn, cucurbits, lima and snap beans, peas, and other crops. Cabbage maggots can cause serious damage to transplants of cabbage, broccoli, cauliflower, and Brussels sprouts and make the fleshy roots of radishes, turnips, and rutabagas unmarketable. Onion maggots are pests of seedling onions, developing bulbs and onions intended for storage. Seedcorn maggot flies emerge in April and May and lay eggs preferentially in areas with decaying organic matter. Fields that are heavily manured or planted to a cover crop are more likely to have seedcorn maggot injury. Maggots burrow into the seed and feed within, often destroying the germ. The seeds fail to germinate and plants do not emerge from the soil, leaving gaps in the stand. When infested seeds germinate, the seedlings are weak and may die. Maggots[Read More…]


Figure 3. A cucumber beetle on the 0.7 x 1.0 mm screen (photo credit: John Obermeyer)

One of the most problematic insect pests that organic vegetable growers have to deal with is the striped cucumber beetle. The insect feeds on all the cucurbit crops, but can be particularly devastating to muskmelons and cucumbers because those two crops are susceptible to bacterial wilt of cucurbits, which is caused by a bacterium carried by the beetles. The only way to avoid this devastating disease is to prevent the beetles from feeding on the plants. There are no effective organic insecticides for managing striped cucumber so we have to look for alternative methods. Row Covers: Row covers can be used to physically prevent beetles from feeding on the plants. To be effective, these need to be placed over the plants immediately after transplanting or before direct seeded crops emerge. The edges of the row covers should be sealed with soil to prevent the beetles from crawling under the fabric[Read More…]


It’s that time of year, where we are prepping high tunnels and getting back into the full swing of production, slowly, here in the Midwest. Many of you have already begun to transplant and may have encountered your first pests on these new crops. Aphids are one that remain a problem in high tunnels, and may even have plagued your winter production (Figure 1,2,3). Some keys to preventing or controlling these pests rely first on sanitation and then careful scouting. Try to remove any green bridge material that may already be infested before transplanting into the space. This includes weeds, lingering winter crops or residues. Having a week without vegetative hosts should get rid of any overwintering residents. After transplanting scout diligently, at least weekly, or more often on susceptible young transplants. Aphid infestations tend to begin on the growing points or younger tissues of the plant. Be sure to[Read More…]


Figure 1. A pheromone trap in the field.

One way insects communicate with individuals of the same species is with pheromones. Pheromones are volatile chemicals released by an insect that usually can be detected only by individuals of the same species. There are a number of different types of pheromones, but the most common type is the sex pheromone. Usually the females will emit a tiny amount of a chemical that attracts the male to her and increases the likelihood of mating. Because the chemical is volatile, air currents carry it. The male detects the pheromone in the air with receptors on his antennae. He then flies upwind to find the source of the pheromone, a prospective mate. The chemical compositions of pheromones for a number of pest species have been identified and synthetic copies can be produced in the laboratory. Synthetic pheromones can be used in conjunction with traps to catch male insects. Listed below are some,[Read More…]


Figure 1. Corn Earworms

Now is a good time to begin your plans for managing corn earworms (Figure 1) in your sweet corn. Below are several tips that will help you in this process: Make sure you have a corn earworm pheromone trap and earworm pheromones. See the article below for details. Consider planting Bt sweet corn, especially for your later plantings that will be harvested in late July and August. If you choose to do so, use varieties that contain two sources of the Bt protein, including the Vip3A protein found in the Attribute II series. Varieties that only contain Cry1Ab proteins do not effectively control earworms in most instances. If you use a Bt variety, maintain a normal insecticide spray program. It’s not a good idea to think that the Bt genes will provide complete control. The combination of Bt and insecticides will help overcome the high populations of earworms late in[Read More…]


Populations of earworms, as evidenced by pheromone trap catches, have not gone to zero as the often due in July. Catches have been fairly low, but moths are still flying and presumably laying eggs. The good news is that in most areas, dent corn is silking, which attracts most of the moths away from our fields of sweet corn and other vegetables. For sweet corn, we would expect pheromone trap catches of less than 10 per night to be safe from damaging infestations of earworm. This is often a good time for growers to avoid the time and expense of spraying their sweet corn. Other vegetable crops such as tomatoes and peppers are less attractive to the moths for egg laying than sweet corn, so they are unlikely to suffer damage when the neighboring field corn has fresh silks present.


There are three important caterpillar pests of crucifers in Indiana, the imported cabbageworm, the cabbage looper, and the diamondback moth. Each of these caterpillars will feed on leaves and heads. All are capable of producing serious damage to most crucifers. The adult imported cabbageworm is a common white butterfly with black spots on the forewing that can be observed flying early in the spring. The larva is a sluggish green caterpillar (Figure 1), exceeding 1 inch in length at maturity, with a light yellow stripe running down its back. The larvae can consume enough leaf material to reduce plant growth; can feed on the head, making it unmarketable, and can foul the head with excrement. The cabbage looper does not overwinter in Indiana, but flies into the state each spring from more southerly locations. Larvae are light green with a white stripe along each side of the body. They reach[Read More…]


Figure 1. The small hole on pepper fruit is likely caused by corn earworm (photo by Wenjing Guan)

European corn borers used to be a serious pest of peppers. The larvae would burrow into the fruit under the cap, making it difficult to cull out infested fruit. With the widespread adoption of Bt corn by agronomic farmers, populations of corn borers have been greatly reduced. However, it appears that in the last couple of years, corn borers have been making a comeback, so management of this pest is still recommended. Corn earworms can also attack pepper fruit. They usually tunnel into the side of the fruit, making it easier to cull out infested fruit. Sometimes when fruit have been treated with insecticides, the larvae will die before they enter the fruit, leaving behind a feeding scar that will render the fruit unusable for fresh market sales. Corn borers can be controlled with Ambush®, Avaunt®, Bt®, Baythroid®, Brigade®, Coragen®, Entrust®, Exirel®, Intrepid®, Lannate®, Mustang Maxx®, Permethrin®, Radiant®, and Warrior®.[Read More…]


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