2018 Hudson Valley Crop Assessment for Thinning
May 21, 2018
During our tour of Hudson Valley orchards on Tuesday, we observed:
- Overall, good return bloom on most varieties, especially when considering the large 2017 crop.
- Honeycrisp were generally good with some light blocks where thinning was insufficient last year.
- Some Fuji, Red Delicious, Golden Delicious, and Jonagold blocks have poor return bloom.
- There were plenty of opportunities for good pollination, so a strong set is expected.
- Depending on the variety and site, southern locations were approaching petal fall, northern locations were around petal fall king bloom.
- Plenty of microclimate variability between sites, local scouting of blocks is essential.
- Where we could tell, set appeared to be strong, plenty of 4's and 5's.
- Severe storm activity on Tuesday afternoon from Albany, south. One location was hailed severely, but the hope is that at this early stage, a marketable crop will make it through.
- Can we summarize two days of scouting and meetings in a single phrase? "Be prepared to thin early, thin hard, and thin often".
- A bloom (now past in the HV) application of NAA at 10 ppm was a good idea this season, especially Gala.
- We recommend an intensive block-by-block scouting to make good thinning decisions, and be aggressive when heavy bloom and good set are evident.
- Use the Cornell Carbohydrate Model to adjust rates for 8 - 12 mm thinning. However, use full rates at petal fall.
- A reminder that old trees on more vigorous rootstocks thin easier (MM.111, MM.106, M.7), lower rates may be more appropriate in these orchards. Trees on M.9 clones, Bud.9 and G-series rootstocks set more fruit and thin harder. Young trees thin very easy, see the guidance for young trees in the "Thinning Suggestions" article below.
- There is a window for thinning Thursday afternoon and Friday of this week. Temperatures will cool off for Friday and Saturday, then rise back up into the 70's for next week. Not ideal conditions for 6BA products (MaxCel, Excilis 9.5SC, Exilis Plus) were we like to see three consecutive post-application days of 70+F temperatures, but just fine for NAA, and if you are in petal fall, carbaryl.
Do not skip the petal fall spray thinning spray due to the cool temperatures forecasted, Recall that last year we did see solid thinning activity from NAA/carbaryl combinations even though the weather was cool and wet.
- At average growth rates, under these forecasted conditions, we can expect orchards at petal fall today will reach 8 mm on next Tuesday, although the strong set (4's & 5's) may slow that pace a bit.
- The weather forecast next week looks excellent for 6BA thinners. However, weather forecasts have been highly inaccurate this season, and are likely to change. Also, the forecasted weather looks to be excellent for carbohydrate production, which suggests that trees will be more difficult to thin.
- Our strong recommendation is to start thinning now (if not sooner), and don't wait until 8-10 mm.

