In southern Wisconsin we are approaching 20 mm fruit size, which means the window for thinning is almost over. For those orchards that still need to get more thinning done, we have very few options left, since once fruit is over 16 mm size, they become less sensitive to chemical thinners, and thus more difficult to drop. In addition to fruit becoming less sensitive to chemical thinners, looking at the weather forecast and the NEWA carbohydrate model, we will not be having any carbohydrate deficit that could help get more fruit off the trees. In fact, temperatures during the weekend and next week will be mild and we will have a carbohydrate surplus, which complicates the situation for those growers that still need to do more thinning. My recommendation is to spray as soon as possible before fruits get to the 20 mm size. This weekend we will have nice weather, and growers should take advantage, because waiting to get warmer weather to drop more fruit will not be an option given the mild temperatures in the forecast.

Here are a couple of for thinning at the 18-20mm stage:

Maxcel (64oz/100 gal TRV dilute basis) + Sevin (1pt/100gal TRV dilute basis) + Oil (1pt/100gal water **don’t concentrate oil**).

For Gala use Maxcel at (64oz/100 gal TRV) + Accede (400 ppm or 46 oz/ac)

Honeycrisp Maxcel (48oz/100 gal TRV) + Accede (300 ppm or 36 oz/acre)

Other cultivars that are difficult to thin go with Maxcel 64 oz TRV plus 400 ppm Accede

This article was posted in Apples and tagged Amaya Atucha, apple thinning, Apples.