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Healthy Fruit 2009 Vol. 17:6

May 12, 2009

Current (May 10) degree day (DD) Accumulations

Location: UMass Cold Spring Orchard (CSO), Belchertown, MA

  • Base 43: 461
  • Base 50: 240

Significant upcoming orchard events based on degree days (Base 43):

  • codling moth 1st catch: 397–581
  • spotted tentiform leafminer sap-feeders present: 343–601
  • McIntosh at petal fall: 445–523
  • Oriental fruit moth 1st flight peak: 344–542
  • plum curculio oviposition scars present: 485–589

Current bud stages

McIntosh apple --
fruit set
Bartlett pear --
fruit set
PF-14 Jersey
peach -- fruit set, shucks on
Cavalier sweet cherry -- fruit set


Mcintosh Apple Fruit Set Bartlett Pear Fruit Set Jersey Peach Fruit Set Cavalier Sweet Cherry Fruit Set

Note: this will be the last bud stage update for 2009.

The way I see it

Well, petal fall on McIntosh is officially May 11 in Belchertown. (One week after bloom.) Last week was a bit challenging for scab and potentially fire blight. There was a 'mammoth' scab infection period during the period May 4 to 9. You should have been well protected and/or applying fungicides during this wet period. And, the fire blight risk ramped up a bit Friday into Saturday, however, it's likely infection did not occur, at least in Belchertown. Overall the bloom seemed good and there was decent weather spurts during bloom, so we can expect to have set a good apple crop (as well as peaches and cherries).

The petal fall period in apples is important for two reasons: it's the beginning of real insect management season, and the start of fruit thinning. More on these follow.

J. Clements

Petal fall thinning and growth control

This, passed along by Duane Greene as a quick reminder about some timely petal fall applications to start the fruit thinning train and for shoot growth control:

"There are two significant timely things that should this week. First, now is about the timing, at least around here for petal fall sprays. Growers have 4 options:

  • Carbaryl (Sevin XLR Plus recommended) alone at 1 quart per 100 gallons dilute. Note that a rate of 1.5 quart/100 gallons dilute is necessary for plum curculio control according to the label.
  • NAA (Fruitone-N or Fruitone-L) alone at about 12 ppm. That is equivalent to just shy of 5 oz (N or L) per 100 gallons dilute.
  • Carbaryl + NAA. If using this combination, back off on the rates of both, i.e., Sevin XLR Plus at 0.5 quart plus NAA at 7.5 ppm (3 oz.) per 100 gallons dilute. Note the lower rate of Sevin XLR Plus will give you minimal (if any) plum curculio control.
  • or NAD (Amid-Thin W) at 25-50 ppm (4 to 8 oz per 100 gallons dilute). Do not use on Delicious. Recommended as a start on Macoun and other early (or all) varieties. Often underlooked as a petal fall spray, it can also be used in combination with carbaryl.

Note that these options are centered around McIntosh thinning, and varieties differ greatly in their susceptibility to (in particular) NAA rates.

The second timely item is Apogee application. Now is the time for the first application. Not much has changed as far as the protocol is concerned. An initial rate of 2 to 4 oz per 100 gal is appropriate. Note that Apogee can help suppress fire blight shoot infections too"

Note that the UMass Fruit Advisor has fact sheets with additional information on both these subjects:

F-118R Thinning Apples Chemically

F-127R Apogee -- A New Growth Retardant for Apples

Petal fall bugsies

  • Plum curculio (PC) becomes active at petal fall. As mentioned above, a petal fall thinning spray of Sevin XLR Plus at 1.5 quart per 100 gallons dilute will give 7 to 10 days of PC control. Make sure bees are out of the orchard before applying Sevin because of high bee toxicity. Other PC control options include Imidan, Lorsban 75 WG, Calypso, Actara, and Avaunt. Don't forget about the DD model for predicting when no additional sprays are necessary for PC: that is 308 DD's (base 50) after petal fall of McIntosh. We will let you know when we reach that in Belchertown, or you can use the NEWA Apple Insect Models for MA.
  • European apple sawfly (EAS) are active at petal-fall (and bloom) but are not a big problem in most orchards. The take-home message of EAS is that it is hard to get a spray on soon enough after bloom to adequately address EAS where it is a real problem. A petal fall spray of Imidan, or Calypso/Avaunt/Actara in most cases is helpful. Assail is also good on EAS (but not very good for PC) and would be a good post-bloom, very early petal fall application where EAS is a big deal. Always apply these insecticides when bees are out of the orchard, or not actively foraging (evening is best) and consult the label for specifics regarding bee hazards.
  • Mites can be addressed at petal fall using Agri-Mek, Apollo, Savey/Onager or Zeal if you did not get a good pre-bloom oil spray applied.
  • Obliquebanded leafroller (OBLR) larvae should be visible (and growing larger with warm weather) at petal fall. Scout flower/fruit clusters and shoot leaves for signs of the larvae (rolled foliage) and a 3% infestation rate warrants treatment. Intrepid, Proclaim, and Delegate are newer petal fall control options for OBLR. Note that Delegate and Intrepid also control OFM (see below) and Proclaim is effective on mites. Pyrethroids can be effective but are not favored because of their impact on beneficials. Lorsban 75 WG is another option (and is effective on PC).
  • Oriental fruit moth (OFM) has been more evident in both peaches and apples, and in addition to using mating disruption, a petal fall spray on both peaches and apples to control OFM has become a necessity in some orchards. In peaches a petal fall spray using an OP (Imidan) or pyrethroid (Warrior, etc.) followed by another spray 10-14 days later (shuck split?) is recommended. A second spray using a pyrethroid will also help with tarnished plant bug. On apples, OP's, pyrethroids, Intrepid, Delegate, Assail, Avaunt and Calypso are all control options. Whew!

Please note that I have paraphrased above what was written up by Art Agnello in this week's Scaffolds Fruit Journal, which you may want to refer to for more information. Thanks Art.

J. Clements

EQUIP Organic Initiative

The USDA is setting aside $50 million of funding for a special Organic Initiative through the Environmental Quality Incentives Program (EQIP) to support and encourage organic production.

Growers have just three weeks to apply for this special funding starting Monday, May 11 and ending Friday, May 29.

The Organic Initiative will be administered by the Natural Resources Conservation Service (NRCS). Interested producers should visit their nearest USDA Service Center to determine eligibility. Additional information on the EQIP Organic Initiative is available at: .

State offices of NRCS can be found at this website:

A useful memo about the Organic Initiative is available from the National Sustainable Agriculture Coalition at this website:

Editors note: Thanks to Andrea Szylvian, US EPA Region 1, for this information.