UConn Extension IPM Pest Message & Reports from the Farm for Friday June 5 th, 2015 As requested by growers in evaluations, this year s weekly reports will be a mix of the old Pest Message format and last year s Reports from the Farm. Growers also requested pictures, so if you have great pest pictures to share send them in by Thursday evening. The reports will be edited, compiled and posted/distributed on Friday morning. [Comments or answers in brackets are provided by Jude Boucher, UConn Extension]. Jude Boucher, UConn Extension Popular early season pests this spring include leafminers, cutworms and cabbage maggots. The spinach leafminer has been hitting spinach, beet greens and Swiss chard hard this season as I have received close to a dozen calls and emails about this pest. The larvae/maggots of this tiny fly feed between the upper and lower surfaces of the leaves producing unsightly white scars and rendering the leaves unmarketable. This insect overwinters as pupae in the soil and has 3-4 generations each season. It has shown up early this season, with the first generation eggs appearing in late April and the second generation eggs starting now. The white eggs can be seen in groups of 1-7 attached near a leaf vein on the underside of the leaves before the larvae hatch and enter the leaves. Because the damaging stage of the insect resides within the leaf and enters from the underside, the most effective insecticides are either systemics or those that can penetrate into the leaf to some degree. Some products need adjuvants to help them penetrate. Note that some products are registered for use on all three of these leafy crops while others are only registered on one or two crops, so pick an insecticide based on the crops that you are growing. Coragen is an example of a systemic product that is registered on spinach, beets and chard, while Radiant or Entrust with an adjuvant, is an example of a product that can move into the leaf to some degree. Time sprays when you see the eggs and try to maximize underleaf coverage. Preventative management techniques include crop rotation and the use of row covers, deep plowing in the spring to bury overwintering pupae, and eliminating weeds that act as alternative hosts such as lambsquarters, nightshade, chickweeds and plantain. Organic growers can also pick and destroy infested leaves or release the commercially available wasp parasitoids Diglyphus isaea and Dacnusa sibirica, which attack young larvae and help keep populations from increasing. Carol Glenister from IPM Supply in Lock, NY says that growers have been happy with results when releasing Diglyphus. Dacnusa may also be needed for cooler temperatures in the early spring. Cutworms are also very abundant this spring. The three large larvae pictured here feeding on asparagus are the spotted cutworm and are making short work of that grower s crop. Thanks Michaele for the great picture...hope you got them under control quickly. The most common species that we tend to see on vegetable is the charcoal-grey, black cutworm. This pest migrates up from the south in the spring and the larvae are getting near full sized now. They usually climb plants at night and just take chunks out of leaves or cut off whole leaves. One larvae will tend to feed on 3-5 plants in a row. Occasionally, they switch to cutting the stem of the plant and can cause tremendous destruction to crops. They tend to hide 1-3 inches deep in the soil during daylight hours, immediately adjacent to the stem of the plant. Because of this habit, on small plantings you can sometimes control the pest by digging out and crushing the larvae. Harden plants before moving to the field to minimize stem cutting and avoid fields with hay or sod crops
are plowed down in the spring, because cutworms lay eggs in grasses. Synthetic pyrethroids registered for the infested crop, when applied on a warm evening usually provide excellent control. Seduce, the spinosad bait, is registered for cutworm control on a wide variety of crops and is approved for organic applications. Spotted cutworms on asparagus: photo by Michael Williams, Bishop s Orchard, Guilford, CT I ve also had a lot of calls and emails concerning cabbage maggots. New vegetable growers are often unfamiliar with this common Brassica pest, that tends to hit heading Brassica such as cabbage, broccoli and cauliflower particularly hard. When you first start planting Brassica crops you may get a couple of years of CM-free harvests, but eventually this pest will find your crops and start to increase in numbers. There are several generations per year, but it is the first generation that usually hits in early May which causes the most damage. Once soil temperatures exceed 90 degrees F it will kill hatching larvae in later generations unless prolonged wet periods cause the soil temperatures to plummet. When soil temperatures drop in the fall, late-season root crops may be attacked. The adult flies deposit tiny, white, bullet-shaped eggs around the stem of the plants right at the soil line. You can scout for these eggs the first and second week of May and see if you have more than 1 egg per plant. You ll find that some plants have none, others have 1 or 2, but some have up to 20 eggs. When the maggots hatch they move down the stem and eat off the feeder roots as they go. Many maggots per plant means that most or all of the roots will be removed and the plants will wilt, become stunted and then die. Because the number of maggots varies from plant to plant, some uninfested plants will be perfectly healthy, while others in your field are slightly wilted or drastically stunted or dead. To supplement spring egg scouting, you can time the emergence and peak flight of the fly generations by using the NEWA web site to see how many degree days have accumulated on farms near you in CT. The site lists
the degree days for peak flight of each generation. Delaying transplanting operations until after peak flight has occurred can avoid infestations. The flies and maggots can be excluded by a combination of crop rotation and row covers. Although CM is not listed on the Seduce label, this OMRI-approved bait is said to be attractive to flies and do a decent job of controlling the adult CM fly. Conventional growers use a soil drench in early May to soak the entire area of the root ball and protect the roots. Effective drenches include Verimark (very expensive), Coragen, and Lorsban. Growers have mentioned that a soil drench with one of the new products usually also keeps the plants free of caterpillars until harvest. I am currently testing this claim up at the UConn Research Farm. Cabbage maggots have removed all the side feeder roots on this inverted cabbage plant. Photo by Daniel Slywka, Daffodil Hill Growers, Southbury, CT
Three-lined potato beetle. Photo by Ian Gibson Asparagus beetles are active Asparagus rust should be controlled starting after the last harvest of spears. Fred Monahan, Stone Garden Farm, Shelton, CT I drenched my cukes with Montana, a generic imidicloprid, how long should that keep the cuke beetles away for? [Through the first generation of beetles or through late June] I have planted Hubbard squash in pots to put around the perimeter of my greenhouse cukes to try this as a trap crop. 6/6 we have started to harvest cukes (very few) and I did see a cucumber beetle flying around the Hubbard s and the Hubbard plants are not even in the greenhouse yet. So this looks promising.
ECB=6: [European corn borer moths in pheromone traps = almost time to scout whorl/pre-tassel stage sweet corn]. Mid-whorl corn no ECB, just took off Remay. Leaf hopper on beans. Beans are budding. Started under remay. [Once the beans bud the crop yield will not be affected by leaf hopper feeding, so you want to remove row covers before flowering] Steve Bengtson, Cold Spring Brook Farm, Berlin, CT This week many flea beetle and a few leafhoppers were on our eggplant. A spray of Warrior II took care of both. Tomatoes were scouted and no sign of early blight was found. ECB traps were set out on June 6 and checked on Wed. June 11. The highest moth counts that I can remember on our farm on such an early date were recorded. The numbers are as follows: ECB I (Z) 10 moths ECB II (E) 12 moths for a total of 22. Scouting three fields of corn in pre-tassel to late whorl stage resulted in 0% damage [infested plants] in all three fields. The second drip line injection for phytopthora prevention was applied on peppers yesterday. Zampro was used after using Presidio 13 days ago. So far the peppers look fine. [Steve is trying the Phytophthora management recommendations from MI State University that were reported in the March issue of Crop Talk] We are harvesting small daily amounts of summer squash. Lots of small squash sitting there, it seems, just waiting for some heat. In general all crops appear to be growing very well. Brian Kelliher, Easy Pickin Orchard, Somers Flea beetles on tomato and potato. Lots on eggplant. Probably treat because of the eggplant damage. Any suggestions on material? I think you might have said the old SpinTor worked on them or was that leaf hoppers? [yes, the spinosad formulations, SpinTor and Entrust, are very good on flea beetles. Radiant, spinetoram, - not effective on FB. None of these work on leaf hoppers.] Had 10% infestation of very small worms on broccoli. Imported Cabbage Worm? Too small for me to tell. Didn't wiggle fast. 0% in cabbage and kale. Not treating. Jonathan Griffen, Oxen Hill Farm, Suffield, CT We've seen our first generation of potato leafhoppers on young green beans (interestingly not on potatoes yet). Diamond back moths are out, and I've seen a couple of their larvae on
brassicas. Not enough damage yet to warrant any intervention, but with the warming weather, we will certainly keep a closer eye on the fields (and checking undersides of leaves, etc.). Some limited flea beetle damage on arugula and pac choi. We are getting ready to set our Pepper maggot trap/s again. this year - we are going to be growing organic sweet corn!!!! So any advice you can offer on what moth traps we need to purchase, etc. would be greatly appreciated. [Scentry Heliothis traps for ECB and CEW and Green Universal bucket trap for FAW. Order pack of 10 Hercon brand CEW lures and 5 of each type of ECB lure (NY/E and Iowa/Z), plus 5 FAW lures. Store in zip lock bag in freezer, replace on trap every 3 weeks. You will also need one Vapona killing strip for the bucket trap. You can order from Great Lakes IPM in Vestaburg, MI (www.greatlakesipm.com, 800-235-0285) or one of several other IPM supply houses.] I wanted to let you know that Oxen Hill has a farm manager apprentice this year...[she] is getting exposure and experience with EVERY part of our business (the fun, the mundane, and the ugly!), and one area [of] focus for learning and education is pest monitoring and SCOUTING!!! Matt DeBacco, UConn Extension, visiting a new farm in Ashford? Cucurbits: I can say that the striped cucumber beetles are on the hatch as we found quite a lot of them on their squash plants that had recently started feeding as the damage was just noticeable but upon inspection, the insect numbers were high and on the rise. Corn: This probably goes without saying to most growers, but right now crows are on the feed and they did a very good job of picking a small field almost clean. So, if growers are not seeing corn germination in 7-10 days they may want to.[one solution is to stagger tomato stakes up the length of the planting in a zig-zag pattern and run fishing line from one stake to another up the length of the field. Move the stakes to new i.e. corn plantings after plants get tall enough to resist crow attack. The crows can t land safely and stop feeding on your field. Another option is to kill and crucify a crow in your field this only works to repel crows.] Dr. Meg McGrath, Cornell University and Joan Allen, Plant Diagnostician, UConn BASIL DOWNY MILDEW ALERT! Meg emailed about receiving reports from WI, TN, VA, WV, and Canada that plants infested with BDM are being found and sold from big box retail chain stores, much the same way that tomato plants infected with late blight were back in 2009. Meg has also reported finding BDM on plants from their local greenhouses/plant suppliers on Long Island. Joan Allen, from UConn, checked a couple big box stores on her way home from work last night and found plants infected with BDM in CT stores. [In recent years, BDM has spread into New England on the wind during August or September causing wide-spread field epidemics. We have been recommending that folks harvest their basil for pesto the first week of August to avoid most of the problem.
However, with infested plants being sold to homeowners throughout the country, you can count on BDM spreading on the wind, and infected basil plants in your fields before July. More on BDM next week.]