Outlook for next week

This year is starting out reminiscent of last year when we caught some apple scab spores and then had an infection period several days later.  A protectant spray of copper, mancozeb, or ziram before that first infection period and later protectants would have greatly diminished the threat of scab through much of April, but a delayed application after the first infection period required something with some after-infection control to prevent the appearance of lesions and re-infection two weeks later.

A chance of showers from tomorrow evening (Sunday, Mar 20) through Monday evening at temperatures in the mid-40s and warmer could again lead to early infection, assuming that most blocks in the Frederick County are not yet covered with a fungicide. In case there is an infection period, remember that follow-up sprays of copper or an EBDC fungicide alone do not have after-infection control. We have found that Vangard can be tank-mixed with copper or mancozeb to improve after-infection control in these early season situations.

We have applied oil to most of our fungicide test blocks in anticipation of increased mite populations later in the season if we need to step up controls for Brown Marmorated Stink Bug (BMSB). Remember to leave 7-14 days between an oil spray and sprays of captan or sulfur. We did not apply oil to the Red Delicious fungicide blocks to see if increased mite populations will aggravate the Alternaria Leaf Blotch that causes defoliation of Red Delicious, that has been observed for several years and might reappear this year.