94 articles tagged "Insect and Mite Management".

Corn earworm flights are quite variable around the state, but are generally heavy. Counts in pheromone traps are higher in the northern part of the state, with the LaPorte County trap reporting 1422 moths over a 7 day period last week. That’s about 20 X the threshold level. As I wrote in the last newsletter, growers need to be spraying frequently when silks are green during this period of time. If you are growing one of the Bt varieties, especially in the northern part of the state, I would still recommend at least a moderate spray program to ensure that you get the results you are looking for.

After a season of relatively low corn earworm activity, pheromone trap catches have taken a dramatic turn upward, especially in the northern half of the state. Catches of 100-200 moths per night in the trap are not uncommon currently. Keep in mind that the threshold for treatment is 10 moths per night, so these catches would be 10-20X the threshold. At this point, growers with late sweet corn should be beginning treating when about 30-50% of the plants are showing silks. Sprays should be applied every 2-3 days until silks turn brown. It takes 3 days for eggs to hatch so a reasonable question would be, why spray every 2 days?  Really what it becomes at this point is a numbers game. Even the best insecticide applied at the highest rate with excellent coverage will not provide 100% control. When counts are near the threshold the number of escapes is[Read More…]

Figure 2. Fall armyworm feeding on kernels.

Fall armyworms (Figure 1) are only able to survive the winter in extreme southern US, along the Gulf Coast and in Florida. Fall armyworms tend to migrate northward gradually, with each successive generation moving several hundred miles further north. They reach Indiana every year, but their populations are unpredictable in numbers and location. This week we have received reports of fall armyworm infestation in corn from southwest Indiana and northern Elkhart County, so they are throughout the state. However, infestations tend to be spotty, with individual fields or even portions of a field showing damage, with neighboring fields uninfested. Fall armyworms will feed on corn at all stages of development and will feed on all above ground plant parts (Figure 2 and 3). However, their late arrival in Indiana (July-August) means that we are mostly concerned about feeding on kernels in the ear. Because of the higher value of the crop, sweet corn,[Read More…]

Figure 1. Squash bug and its eggs (photo credit John Obermeyer)

Squash bug is the most consistent insect pest of squash and pumpkins and is the most difficult to control. The key to management is early detection and control of the nymphs. The adults are extremely difficult to kill (Figure 1). Foliar insecticides should be applied to control the nymphs (Figure 2) 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.  

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

Hornworms can be pests of tomato and pepper in field grown crops, but for some reason seem to be particularly severe in high tunnels. Hornworms are very large caterpillars, measuring up to 4 inches long (Figure 1), and they can consume large quantities of foliage and will also feed on green fruit (Figure 2). In fields, hornworm damage is usually localized and tolerable, although treatment is sometimes required. In high tunnels, hornworm damage, particularly to tomato, is often severe (Figure 3) and will require several applications of insecticides. In field situations, the treatment threshold is one hornworm per two plants. Since the infestations are often localized, it may not be necessary to treat the entire field. In high tunnels, there is no established threshold, so my recommendation would be to treat as soon as you seen caterpillars or their damage. The good news is that hornworms are fairly easy to control.[Read More…]

Pheromone trap catches of corn earworms have been relatively low in most areas of the state, with northern Indiana having the highest counts. Counts from the Purdue research farms can be seen at https://extension.entm.purdue.edu/cornearworm/index.php. Remember that as the field corn surrounding your sweet corn begins to silk and be attractive to the earworm moths for egg laying, the threshold for treatment in your sweet corn rises from 1 moth per night to 10 moths per night. I would like to express one note of caution about using thresholds. We recently had one trap that on seven consecutive nights caught 9, 7, 5, 9, 6, 7, and 7 moths. On none of these nights was the threshold of 10 moths reached. However, on two night 9 moths were caught and at least 5 were caught on every night. I think it is reasonable to assume that the accumulation of eggs laid[Read More…]

Figure 1. A ladybug feeding on aphids

Supplementing the natural enemy population to control insect pests, i.e. augmentation biological control, is of interest to many high tunnel producers. Augmentation biological control has proven very effective at managing a number of greenhouse pests and there are a variety of commercial suppliers. For high tunnels, the greatest challenge is keeping the released predators or parasitoids inside the tunnels and choosing agents that are effective under high temperatures, during the peak of the growing season. We have evaluated some of the more common control agents in high tunnel cucumber and tomato production. The convergent ladybug, Hippodamia convergens, is not grown in a growth facility but rather caught in the wild in the western U.S. (typically California) and shipped throughout the US for control of aphids in particular. They are a fairly inexpensive predator (1500 for about $15.00), the immature form (larvae) and adults feed on aphids (Figure 1). However, you[Read More…]

Figure 1. Colorado potato beetle larvae found on high tunnel tomatoes.

Last week we had a report of an infestation of Colorado potato beetle larvae on tomatoes in a high tunnel (Figure 1). Potato beetles are a pest of most of the solanaceous crops (potato, tomato, eggplant, pepper), but they rarely become a serious problem on tomato in Indiana. In addition, we have not seen them in high tunnels before, so this is a new problem for us. There are a number of insecticides that are labeled for use on Colorado potato beetles, but that list gets much shorter when the problem is in a high tunnel. Remember that in Indiana, a high tunnel is considered a greenhouse, so insecticides that are prohibited in greenhouse cannot be used in high tunnels. The effective products that could be used in this situation are Admire Pro®, Intrepid®, Entrust® and Exirel®.

Figure 1. Aphids on tomatoes in a high tunnel (Photo credit Wenjing Guan)

We have begun to receive the first reports of aphid outbreaks in high tunnels on tomato, pepper, and cucumber (Figure 1). Aphids are a very common problem in high tunnels because the covering excludes rainfall, which is a major mortality factor for small insects like aphids. Some growers are interested in using biological control in their high tunnels because the ability to contain natural enemies within the tunnels increases the likelihood of achieving control. Based on our experience, we believe that lacewing larvae hold the greatest promise for successful biological control of aphids in high tunnels. Because they don’t fly, they are less likely to leave the high tunnel than many other biological control agents. There are a number of biological control suppliers who can provide lacewing larvae for growers. For growers interested in chemical control, some of the insecticides that could be expected to provide good control and are[Read More…]

I continue to catch low numbers of corn earworm moths in my pheromone trap. Although the numbers are low, growers with very early sweet corn that is in the reproductive stage should be alert for potential damage. The threshold for spraying sweet corn that matures prior to field corn silking is only one moth per night. My cooperators at the Purdue Ag Centers around the state are putting up their earworm pheromone traps today (June 6), so by the time you receive this newsletter, we should have data available on moth catches around the state, which you can access at https://extension.entm.purdue.edu/cornearworm/index.php. As I suggested in the last edition of the Vegetable Crops Hotline, I have found corn earworm larvae feeding in the whorl of my knee high sweet corn, planted April 18.

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