Insects.
Bloom has progressed quickly, and so has berry set. Be aware of pinheads and developing fruit and get ready to apply your Altacor fruitworm management spray soon! Timing at 50% out of bloom has already come and gone for some super hybrids but many varieties will reach this point next week!
Disease.
Most growers applied their second fungicide spray this week and will be approaching the 7–10-day retreatment window next week. Given the poor keeping quality forecast, and the speed of bloom progressing, it would be wise to be sure to get your next fungicide on ASAP! Some (but not all) handlers have eased restrictions on mancozebs as a result of recent changes in the European Union MRL.
Weeds.
With a recent change in the European Union MRL for quinclorac, some (but not all) handlers are changing their restrictions for QuinStar. If a handler is making a change to restrictions, they will notify their growers.
QuinStar can be used after bloom to manage yellow loosestrife and other weeds. There will be more in-depth information regarding QuinStar in the next UMass Cranberry Station newsletter (coming out soon).
Poverty grass is at an active growth stage in many locations, and this would be the time to apply a grass herbicide for maximum efficacy. If you can treat it at least twice, you will get better control. While most growers choose to wait until after bloom to apply herbicides, we have not experienced or heard of growers having issues with using Intensity One or Callisto during bloom, and NIS appears to be safe for use with these herbicides during this timing too.
Fertilizer.
Most beds are at or close to being at 75% bloom, and many growers have been applying their early-set fertilizer. The traditional cranberry plant nutrition recommendations is to apply 50-60% of the total nitrogen needed for the season at the early set application, and the remainder of the nitrogen needed at 75% out-of-bloom (late set). Some growers manage the “super hybrids” a bit differently by applying at first fruit set, followed by 2 more doses at 7-day intervals.
Since there are many different formulations of fertilizer available that provide differing amounts of nitrogen, phosphorus, and potassium (N-P-K), remember to calculate the actual of amounts of N and P that you had applied and plan to apply to make sure you are within your target rates for those nutrients. See page 89 of the Chart Book for the formulas to calculate the amount of N, P, and K being applied based on the formulation of fertilizer you are using.
Please reach out to Peter peterj@umass.edu if you have any questions regarding fertilizer rates and applications.
