Options for the Petal Fall Spray

• First, calculate your TRV. You need to know how much product your trees will need.

• Check out the handout that was distributed during the meeting, titled Spray Mixing Instructions Considering Tree Row Volume.

• Read the our TRV article posted to the Cornell ENYCHP website here:

• Carbaryl - it is a mild thinner and it will hardly over-thin (except Cortland). Be sure you have all bees out before spraying Carbaryl.

• Amid-Thin- This is a mild thinner that can be used at bloom and petal fall.  It should be used at the highest label rate suggested, 8 oz/100 gal TRV dilute. A surfactant could be included in the tank.

• NAA- When more aggressive thinning is required, NAA is frequently the thinner selected. It is not so aggressive at petal fall as compared with when it is applied at the 7 to 14 mm fruit size stage.  During bloom and petal fall it can generally be safely used at a rate of 10 ppm without over thinning.   Add 1 pt Sevin (TRV dilute) for harder to thin cultivars.

• Maxcel at 100ppm (64oz/100gal TRV dilute) + 1 pt Sevin (TRV dilute) is a good option for Gala to get some sizing.

When fruit-set is clear, and if heavy on hard-to-thin varieties such as Gala or on biennial bearing varieties such as Honeycrisp, Macoun and Golden Delicious we are recommending to use 7.5 to 10 ppm NAA plus 1pt Carbaryl /100 gallons TRV dilute at petal fall.

Thinning Recommendations for the Petal fall and 8-12 mm spray (when indicated) in 2018:

Varieties where we like Maxcel + Sevin

·        Gala - Promalin at Pink to Full Bloom of the King flower, 64 oz Maxcel (100ppm BA) /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute at Petal and again 8-12mm size. You can also use 7.5ppm NAA + 1pt Sevin/100 gal TRV dilute at petal fall and come back at 8-12mm size with the Maxcel option.

• Empire - 48 oz Maxcel (75 ppm BA) /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute (petal fall and 8-12mm size).

·        Jonamac - 48 oz Maxcel (75 ppm BA) /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute

·        Macoun - It has to have a petal fall spray to stimulate return bloom (7.5ppm NAA plus 1 pint Sevin/100 gallons TRV dilute). At 8-12mm use 48 oz Maxcel (75 ppm BA)  /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute

·        Fuji - Bloom 4 ounces NAA (10ppm) /100 Gallons TRV Dilute, then 48-64 oz Maxcel  (75-100 ppm BA) /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute (petal fall and 8-10mm)

·        Red Delicious - 48 oz Maxcel (75 ppm BA) /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute. Do not use NAA because of pygmy fruit formation. A dose of 1pt Sevin/100 gal TRV dilute would work if fruit set is low and you want to break clusters.

·        We like the 1 pint of Promalin at full bloom, you get some fruit typiness but furthermore you get some thinning.

Varieties where NAA works well

·        McIntosh - respond well to both Maxcel and NAA. So, 2oz Fruitone L or Pomaxa (5ppm NAA)/100 gal TRV dilute + 1pt Sevin/100 gal TRV dilute will work great. AceyMac thins harder than the true Macs - 7.5ppm NAA + 1pt Sevin.

·        Honeycrisp - mature Honeycrisps are hard to thin because of the vigor level of the tree - less competition. Use 3oz Fruitone L or Pomaxa (7.5ppm NAA)/100 gal TRV dilute + 1pt Sevin/100 gal TRV dilute. Put 10ppm NAA at bloom and 7.5ppm NAA + carbaryl at PF and again at 8-12mm. It will help flower initiation.

·        Cortland - It doesn't like carbaryl and it thins very easy, so use 2oz Fruitone L or Pomaxa (5ppm NAA)/100 gal TRV dilute at 8-12 mm size.

·        Gingergold - 1oz Fruitone L or Pomaxa (2.5ppm NAA)/100 gal TRV dilute + 1pt Sevin/100 gal TRV dilute at 8-12 mm size

·        NY1 and NY2- according to our 3rd year trial both varieties are responding well to either BA or NAA (Maxcel is preferable due fruit size): 64 oz Maxcel /100 gallons TRV dilute + 1pt Sevin/100 gal TRV dilute OR 3oz Fruitone L or Pomaxa/100 gal TRV dilute + 1pt Sevin/100 gal TRV dilute (petal fall and 8-10mm). NY2 can be biennial if over-cropped.

·        Golden Delicious - If you use Provide to control russeting at petal fall, then Golden thins easier and 10ppm of NAA (4oz Fruitone L or Pomaxa /100 gal TRV dilute) + 1pt Sevin/100 gal TRV dilute is ok, otherwise put 15ppm NAA on. Maxcel works OK on golden, but it is the toughest variety for Maxcel to thin well - 64oz.

·        Rome Beauty -5ppm NAA (2oz Fruitone L or Pomaxa /100 gal TRV dilute) + 1pt Sevin/100 gal TRV dilute (spur type use 7.5ppm NAA) - 8-12mm.

·        Northern Spy - it is a biennial, and it needs a bloom or petal fall with 2oz Fruitone L or Pomaxa (5ppm)/100 gal TRV dilute + 1pt Sevin/100 gal TRV dilute.

·        Idared: It thins very easily. Use 2.5ppm NAA (1oz Fruitone L or Pomaxa /100 gal TRV dilute) + 1pt Sevin/100 gal TRV dilute at 8-12mm.

·        Jonagold: use moderate rates 7.5ppm NAA (3oz Fruitone L or Pomaxa /100 gal TRV dilute + 1pt Sevin/100 gal TRV dilute) at 12-14mm - one time.

·        Pink Lady: it thins very easy. Use 2.5 to 5ppm NAA (1oz to 2oz Fruitone L or Pomaxa /100 gal TRV dilute) + 1pt Sevin/100 gal TRV dilute at 8-12mm.

Thinning Without Carbaryl

• Use the same rates at petal fall and 10-12mm

• As a rule of thumb 7.5ppm NAA can replace 1pt carbaryl in moderate to hard-to-thin varieties. However, this does not apply for varieties such as Fuji and Red Delicious as pygmy fruit may result.

• HC - 32oz Maxcel + 3oz Fruitone L/100 gal TRV dilute

• Gala -  64oz Maxcel + 3oz Fruitone L /100 gal TRV dilute

• Empire - 48oz Maxcel + 3oz Fruitone L/100 gal TRV dilute

• Macoun - 3 oz Fruitone L (7.5ppm NAA) + 48oz Maxcel /100 gal TRV dilute

• Golden Delicious - 3 oz Fruitone L (7.5ppm NAA) + 48oz Maxcel /100 gal TRV dilute, or a long time program used in NJ for Goldens is at 8-12MM use ½ pint of Ethephon /100 gal TRV dilute plus 4 ounces of NAA (10PPM NAA) /100 gal TRV dilute

• Jonagold - 3oz fruitone + 32 oz Maxcel/100 gal TRV dilute

• NY1 and NY2 = 64oz Maxcel + 3oz Fruitone L /100 gal TRV dilute

• Red Delicious and Fuji - start with a petal fall spray using 8oz Amid Thin//100 gal TRV dilute. Then two shots of 48-64oz Maxcel alone - one at petal fall and another one right after at 8-10mm for Red Delicious and Fuji.

• It might be good to use 10ppm NAA/100 gal TRV dilute at bloom on Fuji, but we do not have any data to support. 

• Amid Thin at 8oz/100 TRV dilute is a good option for bloom and petal fall for all varieties, including Fuji and Red Delicious as it's not known to cause pygmy fruit.

Chemical thinning program for Young Trees:

• For newly planted trees where you desire to totally eliminate the crop try a high rate of Maxcel (64 ounces) + Sevin (2pts) + Oil (1pt) /100 gallon TRV dilute when fruit size is 8-10mm. Or , as soon as the bees are out, begin repeated heavy doses of carbaryl (2 pints/100 gallons) tank-mixed with Regulaid (1 pint/100 gallons).

• For 2nd year trees where we want a small crop use only hand thinning and the Cornell young tree thinning guide to adjust crop load. 

• For 3rd year trees use Sevin alone + follow-up hand-thinning.

• For 4th year trees use 1/2 of our suggested full rate of NAA + Sevin or Maxce l+ Sevin.

• For 5th year trees use 75% of a full rate of NAA + Sevin or Maxcel + Sevin.

• For 6th year trees use a full rate of NAA + Sevin or Maxcel + Sevin.

Cautions

• We suggest that Captan not be added to or near thinning sprays.