65 articles tagged "Insect and Mite Management".

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…]


When we first began working in high tunnels about 8 years ago, most of the popular literature said that the tunnels would provide protection from most insect pests, other than the usual greenhouse pests like aphids and mites. What we found very quickly is that that information was untrue. We found very high populations of a variety of insect pests within our high tunnels. Caterpillars of various types seem to be especially problematic in high tunnels. Our theory is that the moths fly into the tunnel and can’t figure out how to escape, so the females just lay their eggs on the crop they can reach. The key to managing these caterpillars is regular scouting and treating early. For the crop you are growing, look for the products recommend in the Midwest Vegetable Production Guide for caterpillars, then check Table 16 on page 45 to see if it can be[Read More…]


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In southern Indiana, we are between generations of striped cucumber beetles. That doesn’t mean there are none out there, but numbers are lower than they were and lower than they will be. The second generation should be coming out soon. Northern areas are a little behind. The biggest concern we have with the first generation or overwintering cucumber beetles is their ability to feed on seedlings and to transmit the pathogen that causes bacterial wilt to cantaloupes and cucumbers. For the second generation, we are less concerned about bacterial wilt and more concerned about feeding damage to the fruit, particularly watermelons and cucumbers. If you are seeing beetle feeding on fruit, you should probably apply an insecticide to protect the fruit. If not, you are probably safe not spraying. For later planted pumpkins, the biggest concern is feeding on the plants in the seedling stage. Once the plants get larger,[Read More…]


Figure 1. Corn Earworms

The first generation flight of corn earworm moths continues throughout the state. Heaviest populations as evidenced by pheromone trap catches have been in the northwest. This first generation flight should be ending soon. Then we will likely have a lull in catches for a while (several weeks) until the second generation emerges or we get a migratory flight from the southern US. To check moth catches in your area, please visit https://extension.entm.purdue.edu/cornearworm/index_doc.html. Remember that sweet corn that silks prior to silking in the dent corn near your sweet corn field is much more vulnerable to egg laying from the moths. That’s why we recommend spraying if your sweet corn is silking and you catch any moths in your trap. Once the neighboring dent corn begins silking, that corn will be just as attractive to moths for laying eggs as your sweet corn, so the amount of egg laying is diluted.[Read More…]


Figure 1. Hornworm feeding on tomato leaves in a high tunnel.

One of the most impressive insect pests that we deal with on vegetables are the hornworms (Figure 1 and 2). These two species, tomato and tobacco hornworm, can reach up to 4 inches long and consume massive quantities of foliage and fruit. In recent years, we have seen damage in high tunnels that is more serious than we normally see in field situations. The good news is that despite their size, hornworms are relatively easy to kill. A wide variety of insecticides will control them. See pages 143-44 in the Midwest Vegetable Production Guide for choices. As with most pests, it is better to treat when the hornworms are small because they are easier to kill and because you can avoid most of their damage. Hornworm damage is usually fairly easy to see, either because of the defoliation or the frass (insect poop) that they leave behind. So, scout regularly[Read More…]


Figure 2. Squash bug nymphs (photo credit John Obermeyer)

Squash bug is the most consistent insect pest of squash and pumpkins and is the most difficult to control (Figure 1 and 2). The key to management is early detection and control of the nymphs. The adults are extremely difficult to kill. Foliar insecticides should be applied to control the nymphs when you have more than an average of one egg mass per plant. When you find egg masses, mark them with flags and check every day or two to see when they hatch. When many of the egg masses are hatching, that is the time to begin application. Since eggs are laid and hatch over an extended period of time, several applications may be required. Brigade®, Mustang Max® and Warrior® have provided excellent control.


I have received some reports of Colorado potato beetles damaging both potatoes and tomatoes, including tomatoes in high tunnels. Both the adults and larvae are voracious feeders. As with most pests, it is best to get potato beetles under control before the populations get too high. Also, killing small larvae is easier than killing large ones, so spraying earlier will provide better control. We have had numerous reports of resistance to the pyrethroids in Indiana, so I generally don’t recommend those products. If you try one and it works, then you probably don’t have a resistant population at this point. For most of the state, I recommend one of the following products, Admire Pro®, Agri-Mek®, Assail, Coragen®, Exirel®, Radiant®, and Rimon®. Note that Coragen® and Radiant® cannot be used in high tunnels.


Corn earworms are flying. I had 10 in my pheromone trap this morning (June 20). With the surrounding dent corn in most areas far from producing silks, the threshold for spraying silking sweet corn is 1 moth per night, well below what we are catching. So growers who have sweet corn with fresh silks are in danger of suffering serious losses if they don’t control the earworms. Because of problems with resistance to the pyrethroid insecticides, the best products available are Coragen® and Radiant®. Note the limitations on the number of applications or amount of product allowed. You may need both products to complete management on a particular planting. Begin spraying when 30-50% of the plants in your field are silking. Continue to spray every 3-5 days until the silks turn brown. To see corn earworm trap catches around the state, go to https://extension.entm.purdue.edu/cornearworm/index_doc.html.


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