Dr. Terence Robinson and Mike Basedow

Below is a review from our virtual Fruit Set Meeting that we held on May 29th.  The recording of which can also be viewed below:

Assess each block for set and thinning achieved so far.

Depending on your return bloom and the thinning program that you’ve used to date, some blocks are likely to require more thinning than others at 12mm.  Assess each variety by block closely to come up with your best thinning strategy.

Apply your thinners when king fruits are 10-13mm. You can also use the NEWA  carbohydrate model degree day calculator to target the best time for thinning. The 10-13mm thinner spray timing generally falls to when DD accumulations after full bloom are between 200-250 DD.  

In Peru, the 10-13mm thinning window is likely falling between May 31 and June 4th. Based on the weather conditions, we believe the best window to make these applications will fall early next week, from Monday to Wednesday. Below is the current output from Peru with a Mac full bloom date of 5/12.  Late bloom varieties like NY-1 will likely be a day or two further behind. Given the variability of bloom dates by variety and farm, we strongly encourage you to look at the carbohydrate model for your area with your bloom dates.

At 10-13mm, all thinners have a strong effect and are usually quite effective. Unfortunately, the carbohydrate model predicts we will likely be in a carbohydrate surplus during our 12mm window, which will likely give us very mild thinning.  Use the carbohydrate model to adjust your timing and rates. That being said, things can change, so check the model with your green tip and bloom dates by variety ahead of your applications.

Here are our full rate recommendations for select varieties. 

• Honeycrisp – Use NAA at 3oz  per 100 Gallons Tree Row Volume Dilute (TRVD) basis + 2 pt Sevin XLR per 100 Gallons
• McIntosh – Use NAA at 2oz per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• Gala – Use Maxcel at 64 oz per 100 Gallons TRVD basis + 2 pt Sevin XLRper 100 Gallons
• Fuji -Use Maxcel at 64 oz per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• NY1 – Use Maxcel at 48 oz per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• Empire – Use Maxcel at 64 oz per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• Spur Delicious – Use Maxcel at 64 oz per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• NY2 – Use NAA at 2 oz  per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• Macoun – use NAA at 64 oz per 100 Gallons TRVD basis + 2 pt Sevin XLR per 100 Gallons
• Cortland – use NAA at 2 oz per 100 Gallons TRVD basis
• Pink Lady – Use NAA at 2oz per 100 Gallons TRVD basis + 1 pt Sevin XLR per 100 Gallons

Surfactants like Regulaid, can increase the response of NAA.

If using NAA, add Regulaid to the above rates this year.

Suggested rates are dilute TRV rates. Calculate TRV for each orchard and then a concentration factor:

• TRV/Volume of spray per acre=Concentration factor
• Example: TRV=200 and spray volume is 100 then concentration factor=2

Multiply suggested rates by concentration factor to get rate/acre.

• Example 3 oz NAA X Conc factor of 2=6oz NAA/100 gal X 5 for a 500 gallon sprayer=30 oz/sprayer tank
• Example 64 oz Maxcel X Conc factor of 2=128oz Maxcel/100 gal X 5=5 gallons Maxcel/sprayer tank

Do not use concentration factor adjustment for Sevin or surfactants.

Nozzle the sprayer differently for the next sprays

1.For the 12mm spray, nozzle so that 75% of the spray is directed to the top half of the tree.

2.For 18mm (if needed) only spray the top of the tree.

Questions? Please feel free to reach out to Mike at mrb254@cornell.edu or 518 410 6823.