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Healthy Fruit 2010 Vol. 18:2

Apr 13, 2010

Current (through April 12) degree day (DD) Accumulations

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

  • Base 43: 244
  • Base 50: 120

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

  • Redbanded leafroller first flight peak: 231-367
  • Spotted tentiform leafminer 1st flight peak: 263-387
  • Oriental fruit moth 1st catch: 221-325
  • European red mite egg hatch: 231-337
  • Obliquebanded leafroller larvae active: 158-314
  • Pear psylla 1st egghatch: 174-328
  • McIntosh at pink: 274-312

Orchard Radar

Beginning with this Issue of Healthy Fruit, we will begin publishing a synopsis of Glen Koehler's (U. of Maine) Orchard Radar pest predictions for Belchertown, MA (UMass Cold Spring Orchard). Orchard Radar uses SkyBit data as input for apple pest occurrence and development models. Only select short-term output of particular interest will be reported here. For the complete set of models see the link above. If you are interested in getting Orchard Radar for you location, you may want to contact Glen Koehler,

  • 1st generation OFM flight starts: April 15, Thursday
  • 1st RBLR flight began around April 5, Monday. Peak trap catch and approximate start of egg hatch: April 19, Monday.
  • 1st STLM flight, peak trap catch: April 27, Tuesday
  • Estimated hatch date of overwintered European red mite (ERM) eggs indicating declining efficacy of prebloom oil treatment is Wednesday, April 14
  • Friday, Apr 16 McIntosh full pink-extended

The way I see it

The growing season is app. 2 weeks ahead of schedule. Knock on wood, but other than light scattered frost, real freezing temperatures are not in the forecast. As fruit trees are in bloom or approach bloom, a reminder that a temperature of 28 degrees F. would result in app. 10% flower bud damage while a low temperature of 25 degrees F. would result in up to 90% damage. We'll keep our fingers crossed.

Interestingly, we have not had a significant apple scab infection period to date while significant green tissue has been exposed. (Including late last week's wetting event, at least in Belchertown.) That will change late this week as significant precipitation is expected beginning Friday. You will have to be covered-up with fungicide. Also, stone fruit remains susceptible to brown rot infection through shuck-split during wet weather.

Tree planting tips

  • adjust soil pH to 6 to 6.5 before planting
  • plant in April! Early planting has many benefits, including: delayed bud break so roots have time to become established and grow to support emerging foliage; earlier bloom so risk of fire blight is reduced (assuming bloom is not removed, but it is recommended that bloom be removed to reduce the risk of fire blight infection); and longer growing season = more growth.
  • do not let roots dry out prior to planting; do not store trees with fruit as excess ethylene will stimulate bud-break
  • soak trees in fresh (aerated) water for up to 24 hours before planting
  • don't plant too deep! apple graft union should be a minimum of 4 inches above ground; higher planting will reduce scion vigor if desired; the downside of higher planting is potential for dogwood borer infestation in later years; stone fruit graft union 1 to 2 inches above ground (stone fruit roots should begin 1-2 inches below ground)
  • water trees immediately after planting but don't water again until growth starts
  • wait until trees start to grow before fertilizing; then apply 4-6 ounces of calcium nitrate per tree

Pest watch

  • make sure apple orchards are covered up with fungicide before the next significant wetting event is predicted (later this week); fungicides of choice (by themself or in-combination) at this time of the year include: Captan, mancozeb fungicides (Penncozeb, Dithane, Manzate, Polyram), Scala, Sovran, Vangard, or Inspire Super MP.
  • stone fruit bloom is susceptible to bron rot until shuck split under wet conditions; bloom is the time to get it under control otherwise you will likely struggle with brown rot as fruit matures; fungicides should be applied during bloom if it rains; excellent fungicide choices include: Indar, Rally, Orbit, Elite, Captan (good only), Pristine (good only), and Adament.
  • a pink spray on apple of a pyrethroid insecticide (Ambush, Pounce, Warrior, Danitol) may be warranted if tarnished plant bug is a problem, but such a spray is hard on beneficials; Lannate or Thiodan may also be used; Imidan is ineffective on plant bug
  • Lorsban applied at pink gives some control of rosy apple aphid, green fruitworm, and oblique-banded leafrroller; apply in apple orchards where these pests have been a problem, but the leafollers are not done yet; remember Lorsban can only be used once in a season
  • pheromone traps set out for Oriental fruit moth are useful for determining prevalence, however, most OFM will be controlled with petal-fall sprays; but you can also deploy mating disruption at this time if you choose
  • spotted tentiform leafminer are flying and laying eggs, but this generation is typically not treated
  • mite eggs are hatching soon and an ovicidal miticide (Apollo, Savey, Zea)l can be applied during pinkd if you did not get oil on and you typically have a mite problem; otherwise, you will have to wait and apply a 'rescue' treatment when mites build-up during the summer

Useful links

UMass Extension Fruit Program

Scaffolds Fruit Journal

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