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Many growers have been treating with Avaunt over the past few weeks for winter moth or weevil. Winter moth should be finishing up so it's is time to stop chasing. Weevil has been reported over threshold and it should be treated if you have high numbers. Spag is out and larvae are getting picked up in sweep nets now. We had also heard of high counts (8 larvae) of black-headed fireworm. Marty also reports seeing some weird spanworms out there, but nothing to be worried about. If you are using pheromone traps to time sprays for BHF, Spag or girdler, traps should be out by June 1. Use 1 trap per 10 acres and place them on the upwind side of the bog so that the pheromone blows across your bog. Check them weekly (more or less depending on flight patterns) and clean or change them as needed.
I have had a couple of questions about treating for control of poison ivy. Spot-applications of concentrated rates of Callisto with either COC or NIS give good control. Our 2-year trial showed better control in Year 1 when we treated mid-June/early July compared to late May/mid-June applications, but both decreased PI and cranberry growth rebounded. The difference between the two timings became much smaller in the second year when we treated in 2 consecutive years. The bottom line is if you have poison ivy in spots and have time to treat it, go for it. Two applications per year are recommended and they must be separated by at least 14 days. Use up to 1.5 oz/gallon with either NIS or COC, but if it is looking to be hot and/or you have flowers out there, I would favor the NIS. We have been working with Syngenta and we should have a Special Local Needs label for spot-treatments very shortly.
Early hybrids such as the Mullacas, were in hook stage earlier this week. So, for the very early varieties, first fungicide is just around the corner. We will be having a bogside workshop here on June 9 from 8-10 AM with 2 contact hours offered.
We have heard of very high counts of gypsy moth over the past week. If weevil is not in the mix, Delegate is a good choice for the cutworm pests, as is Intrepid. Sevin can also be a good choice if your caterpillars are dominated by gypsy moths. Humped green fruitworm has also be scouted.
Winter moth larvae are out and growers are spraying to control the immatures. We sprayed Rocky Pond bog in Miles Standish Forest on Monday for WM control. The larvae are very small; using a hand lens or other magnifier to see them, if needed (see pictures on first page of May 1 newsletter). Scouting for other early season insects should be well underway. Although the spring has been cool, native varieties are at 25 F for frost tolerance and the hybrids are at 27 F (cabbage head stage). Carolyn feels that the vines have “caught up” to their average growth stage for early May.
Frost season is underway! As of April 23rd, most bogs had reached white bud stage. Some bogs that iced-out late were lagging behind a bit. Starting on April 27th and updated as the plants advance, photos of tolerance stages will be posted on the Station website.
Winter moth found on cranberry! The Entomology Lab reports tiny winter moth (WM) larvae have been picked up in sweeps in Plymouth and Rochester! Despite temps below 60, a few larvae per sweep net have been found. They are incredibly tiny but they are out.
If you are going to treat for WM, consider Intrepid, Avaunt or Delegate given that larvae can now be found; they will only grow bigger by eating the tiny buds! Although the numbers may be below threshold, they will get into buds and may be harder to kill once inside. The threshold of 18 per sweep set is not a long-standing "tested" number; it is a guideline to help management. Consider only treating pieces where the higher numbers are found and perhaps at reduced rates of insecticide, and then sweep again. Possibly, the larvae are from the bog and a spray would stop them, but it is also possible larvae may come in from surrounding blueberries and trees and may continue "ballooning" in, and maybe both. Another consideration is size of cranberry bud… if the buds are too small, larvae may just die, if buds are bigger (i.e., sanded pieces, early varieties, warm locations) larvae may do well and grow faster.
Heather Faubert, University of Rhode Island Extension reports that winter moth eggs started hatching on April 19. Over the past week, all the eggs at the monitoring tree in Kingston, RI have turned blue and hatched. She expects all eggs have hatched by now in our area as well.
It is still too early to be spraying for winter moth in cranberry, however, we wanted to keep you up to date on WM progress in various spots throughout the region. According to Heather Faubert, University of Rhode Island Extension, winter moth eggs started hatching on Sunday, April 19th in Rhode Island. Many blueberry and apple growers sprayed insecticides over the weekend, protecting flower buds.
As of April 20 (using a base of 40°F starting Jan 1), East Wareham (02538), and Sandwich (02563) had 138 GDD, East Freetown (02717) had 156, Carver (02330) had 129, and South Dennis (02660) had 128. This is still much lower than this time last year (range was 185 to 261 GDD). MA's target for winter moth hatching is 177-239 GDD. To check your area: http://adstest.climate.weather.com/outlook/agriculture/growing-degree-days.
Management: Timing is important because if the newly hatched caterpillars are allowed to crawl inside the expanding buds, they are protected from any insecticide that might be applied. Scouting should be started early (ca. May 1) to catch these populations. Avaunt, Delegate, and Intrepid are the best choices for control of WM on cranberry. If you have a history of WM, you may need to apply a prophylactic spray early in the season. The Action Threshold for WM is 18 average per sweep set.
We do not recommend oils at this time (even though other small fruit growers use them against WM). Marty has not found cranberry to be listed on an oil label (if you know differently, please tell us).
For more information about Winter Moth, see IPM message dated April 9th below.
We sent out a Winter Moth fact sheet in the April 8, 2015 newsletter. Look for it! These photos are included in the fact sheet:
It's not too soon to be thinking about winter moth. We are a bit lucky in that we can usually find WM in blueberry ahead of when they will be in cranberry. However, you can track potential egg hatch yourself. Eggs hatch when temperatures average around 55°F. It is believed that egg hatch in Massachusetts occurs when approximately 177-239 growing degree days (GDD) above a base of 40°F (starting Jan 1) have accumulated.
GDD can be variable. As of April 8, East Wareham (02538), Norton (02766), and Sandwich (02563) have 42 GDD, East Freetown (02717) has 40, Carver (02330) has 27, and South Dennis (02660) has 37. This is much lower than this time last year (range was 89 to 138 GDD). Visit http://newa.cornell.edu/ or http://www.weather.com/outdoors/agriculture/growing-degree-days/01002 to calculate the Growing Degree Days for your location.
Management: Insecticide sprays timed to coincide with egg hatch are the most effective way of controlling this pest. The timing is important because if the newly hatched caterpillars are allowed to crawl inside the expanding buds, they are protected from any insecticide that might be applied. Scouting should be started early (ca. May 1) to catch these populations. Populations may re-occur as larvae can balloon in. Avaunt, Delegate, and Intrepid are the best choices for control of WM on cranberry. If you have a history of WM, you may need to apply a prophylactic spray early in the season. The Action Threshold for WM is 18 average per sweep set.
Organic growers can use Entrust (spinosad), or one of the Neem products such as AzaDirect, Neemix, or Ecozin in place of the insecticides listed in the table above. Products that contain B.t., may also be effective but depend on the caterpillars ingesting enough product to be effective.
For detailed information concerning the biology and management of Winter Moth, visit the following: http://extension.umass.edu/landscape/fact-sheets/winter-moth-identification-management http://extension.umass.edu/landscape/fact-sheets/winter-moth-overview
For current regional updates on the Landscape message:
UMass Cranberry Station • 1 State Bog Road, PO Box 569, East Wareham, MA 02538 • email@example.com • Phone: 508-295-2212 • Fax: 508-295-6387
The UMass Cranberry Station is part of The College of Natural Sciences.