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Cranberry IPM Message

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).

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.

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.

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:

If it has been more than 1 week since your last fruitworm spray, you should be checking fruit for unhatched viable eggs. Do not exceed 19.5 oz per acre per season for Delegate. If you are sweeping, you may see cranberry weevil and flea beetles. Belay can be used but only if the bees are gone as it is highly toxic. Check for handler restrictions for this and other insecticides!

If you are concerned about sprays going out in unstable weather pattern, Altacor should have good residual and rainfastness. Please use the traditional cranberry fruitworm timing for Howes, spraying 7-9 days after 50% out-of-bloom. This is still the best management strategy for this variety.

You may need to be checking early varieties and hybrid varieties soon for %out-of-bloom (%oob). It is always good to get 2 %oob counts BEFORE you hit 50%, just to improve your estimate. Some growers may be spraying for fruitworm control by the end of next week. Late water Howes are very behind. It is too late to be spraying for weevil (unless you have LW Howes).

We have had reports of spag and green spanworm flying in the past week.  Many growers are applying first fungicide (or second fungicides on very early varieties). Try to actually do an “in bloom” count to properly time your first fungicide. If you are applying Select or Select Max, please note that you cannot apply the herbicide between hook and fruit set.

Pheromone traps should be out by now. Place them on the upwind side of the bog so that the scent flows onto your bogs with the prevailing winds. BHF larvae are still being picked up but they should be pupating soon. Spag is also still out but at a size where you can see them.

Scale is showing up more frequently on bogs this spring. 

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