Rick Foster

Professor
Department of ​Entomology
Area(s) of Interest: Pest Mgmt. Vegetable and Fruit Crops
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​Populations of striped cucumber beetles continue to remain high. Muskmelon and cucumber growers should continue to monitor and spray as needed to avoid transmission of the pathogen that causes bacterial wilt of cucurbits. Wilt symptoms are showing up on melons throughout the state at this time, with greater prevalence in the southern counties and less further north. Growers are encouraged to spray as late in the day as possible, preferably after the flowers have closed and the bees have left the field, so that effects on pollinators are minimized.


I’ve seen some substantial populations of potato leafhoppers recently. Leafhoppers can be a significant pest of a number of vegetable crops, with potato and snap beans being particularly affected. Look for adults flitting off the plants when they are disturbed and for nymphs feeding on the underside of the leaves. It is important not to wait until you see symptoms (hopper burn) before you take action. Scouting is the best way to avoid leafhopper injury.


​Yellowstriped armyworms continue to cause problems for tomato growers, especially in high tunnels. The populations are often spotty within a field or high tunnel, but can easily reach damaging levels. Most of the insecticides listed in the Midwest Vegetable Production Guide for control of caterpillars on fruiting vegetables (pages 135-6) will control yellowstriped armyworms. If spraying within a high tunnel, be sure that the label allows use in a greenhouse or high tunnel. Consult Table 16 on page 40 for available options.


After a brief lull in pheromone trap catches, we have resumed catching earworm moths all around the state. Although most of the counts are relatively low (less than 10 per night), remember that for early planted sweet corn that silks before the neighboring field corn silks, the threshold for treatment is 1 moth per night. So, if you have sweet corn that is in the vulnerable stage, green silks present, treatment is justified if you are catching any earworm moths in your trap.


​On May 29, 2015, the EPA issued a proposal to protect bees from acutely toxic pesticides. As stated in the announcement, “EPA is proposing to prohibit the application of pesticides that are highly toxic to bees when crops are in bloom and bees are under contract for pollination services. These restrictions would prohibit application of most insecticides and some herbicides during bloom.” The criteria used to determine which products would be prohibited from use during bloom were 1) Liquid or dust formulation as applied; 2) Foliar use (applying pesticides directly to crop leaves) directions for use on crop; and 3) Active ingredients that have been determined via testing to have high toxicity for bees (less than 11 micrograms per bee). To see the details of the proposal including the list of active ingredients that would be affected by this proposal, go to www.epa.gov/oppfead1/cb/csb_page/updates/2015/protect-bees.html.  These proposed changes have the potential to[Read More…]


​So far it appears that populations of striped cucumber beetles appear to be low to moderate in most areas. The often cool and/or wet weather may be suppressing their activity currently, so be prepared if we get a period of warm, dry weather. Remember that cantaloupes and cucumbers are most susceptible to bacterial wilt, so the threshold for treatment is relatively low, 1 beetle/plant. For watermelons, pumpkins, and most squashes, the threshold is 5 beetles/plant because those cucurbits are less susceptible to bacterial wilt. When treating cucurbits that are in bloom for beetles, growers should wait to begin spraying until the flowers have closed up for the day. Ideally, sprays should be applied late in the evening if possible, because the potential for bee kills are reduced and that will allow for maximum residue levels on the foliage the next day.


​2015 marks the 40th year of my career as an entomologist and I still am surprised on a regular basis by how insects behave. I put out a corn earworm pheromone trap on May 14 and immediately caught 7 moths that night. Over the next three nights, I caught 36 moths. Typically, the few earworms that we would expect to overwinter here in west central Indiana would emerge about June 20. It has not been an unusually warm spring, to say the least, so it is unlikely that those moths emerged locally. The other possibility is migration from southern areas. Earworm moths often migrate in on storm fronts from the south. However, when moths are blown hundreds of miles on storm fronts, their wings usually get a little tattered. The moths I’ve been catching look pristine, as if they just emerged. So, the bottom line is that I have no[Read More…]


​Striped cucumber beetles are emerging from their overwintering habitat in southern Indiana. This pest can damage cucurbit crops in several ways. One that I saw this week is that they can kill young transplants by their direct feeding. Of more critical concern usually is their ability to transmit the bacterium that causes bacterial wilt of cucurbits. Cantaloupes and cucumbers are especially susceptible to this disease. Pumpkins and some of the winter squashes are susceptible when the plants are young. Other squash and watermelons are not affected by the disease. Therefore, based on years of research and experience, we have set the treatment threshold at 1 beetle per plant for cantaloupes, cucumbers, and very young pumpkins and winter squash (less than 3 weeks old). For watermelons, summer squashes, and older pumpkins and winter squashes, the threshold is 5 beetles per plant.  Our research has shown that for cucurbits grown in the[Read More…]


​It’s early in the growing season, but I am already receiving calls about aphids on melons. We had lots of problems with aphids in 2013 and not very many last year. Particularly at this time of year, I’m recommending Assail® for aphid control on melons for several reasons. First, it does an excellent job killing aphids. Second, it will also provide very good control of striped cucumber beetles when they become active in your field. Third, I’ve never been a big fan of pyrethroid insecticides for control of aphids. They work to some extent but we have other products that are better. Finally, the active ingredient in Assail®, acetamiprid, is much less toxic to honey bees than the other neonicotinoid insecticides that could be used for aphid control. If you used either Admire Pro® or Platinum® at planting time, you should receive 3-4 weeks of aphid control. Growers should be[Read More…]


​I have received calls about seedcorn maggots in melons and have seen wireworm damage in my research plots in Vincennes. Seedcorn maggots are usually associated with cool weather since the adult flies will not lay their eggs near melons plants when the soil temperature exceeds 70°F. So the cool weather we have had this past week could promote seedcorn maggot problems. One of the species of wireworms I observed is Conoderus lividus, a species commonly associated with corn. If you are planting melons after corn, the field could be infested with wireworms, although frankly this is fairly rare. You can determine the potential for wireworm problems prior to planting by burying a cup of flour or untreated grain (corn or wheat) about 6 inches under the ground. Come back and dig up the bait in about a week and look for wireworms. About the only product melon growers have available[Read More…]