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Healthy Fruit 2008 Vol. 16:13

Jun 24, 2008

Current degree day accumulations

  • Belchertown, UMass CSO observed (01/01/08 – 06/23/08): Base 43, 1136; Base 50, 692
  • Belchertown, UMass CSO SkyBit (01/01/08 – 06/23/08): Base 43, 1195; Base 50, NA

Upcoming meetings

JULY 17, Summer Meeting of the Massachusetts Fruit Growers' Association, UMass Cold Spring Orchard, 391 Sabin St. (Details TBA, but mark your calendar with the date!)

Observations from Belchertown

Storms continue throught the state, but so far we have been spared here in Belchertown. (Other than lots of rain and lightning on Sunday that both stopped my electronic weather station at work and killed my garage door opener at home!) Others have not been so fortunate. When you get hail damage your first thought should be to contact your crop insurance agent. (Assuming you have crop insurance, which everyone does, right?) Second -- and this is very important if you have had fireblight in the orchard in the past year or two -- you should apply a streptomycin spray within 12 hours of the damage. See 'Get out the strep.' I have found mites in one block of apples that received no oil this spring, so that warrants treatment at this point. Best options include Acramite (Chemtura), Kanemite (Arysta LifeScience), Nexter (BASF), and Zeal (Valent BioSciences. I plan to use Zeal at 2.5 oz/acre which should do a pretty good job clearing them out at this point. J. Clements

Jmcextman blog posts

TUESDAY, JUNE 24, 2008
What shall we do with a drunken sailor...

Get out the strep

It goes without saying that getting hailed in an orchard is a 'trauma' event in more ways than one. Besides calling your crop insurance agent, you should consider applying a streptomycin (Agri-strep, Mycoshield, Firewall) spray ASAP after the event in most orchards to prevent a fireblight outbreak. This is particularly needful in any orchard that has had fireblight in the past year or two, and/or has susceptible cultivars (Honeycrisp, Gala, Golden Delicious, Paulared, Cortland) and rootstocks (particularly M.9). In a recent Scaffolds Fruit Journal article, Dr. David Rosenberger lays out some of the guidelines when using streptomycin for fireblight after hail:

  • apply within 24 hours if at all possible; up to 48 hours may provide some benefit; after 48 hours don't bother applying even if you see fireblight strikes (say, a week later -- it's too late)
  • use 2 lb/acre along with Regulaid or another good spreader
  • preharvest interval is 50 days
  • mature orchards with a full crop are not vulnerable to fireblight infection if terminal buds are set

For more post-hail advice from Dr. Rosenberger see FUNGICIDE CONSIDERATIONS FOR HAIL-DAMAGED ORCHARDS in the June 23, 2008 Scaffolds. J. Clements

Oh, how the cherries they will crack

white gold cherry crack The handful of you that grow cherries seriously are having a tough year, First, a freeze on May 1 hurt some buds -- one cherry block in Belchertown, the crop was reduced by app. 90%. Second, pollenation weather was not all that great, and those that did not get frozen still did not seem to set a particularly heavy crop. (Cherries are difficult to get pollenated despite what appears to be the abundance of wild pollinators during bloom.) Finally, this rainy weather as the crop ripens has resulted in a lot of significant cracking on those fruit that remain.= (Brown rot is showing up in unsprayed trees -- i.e, lightly cropped, it's not worth it -- big time too.) For a good overview of cracking physiology and prevention measures see this article by Matt Whiting of Washington State University. Use of calcium chloride (sprays) seems like a promising option for cherry growers without rain covers. (Is that everyone?) But the calcium chloride sprays have to go on when water on the surface of the cherry is present, and must be repeated each time it rains to be effective at all. Finding the rate(s) to apply with an airblast sprayer has been difficult, but probably 2 to 3 lbs/100 gallons of water is about right. J. Clements

Blast from the past

Reprinted from Fruit Notes, June 18, 1958 (Fruit Notes Archive)

The consumer wants large, well-colored, high quality peaches. Peaches of this type cannot be produced on an overloaded tree. The ability of a peach tree to develop size in its fruits depends upon (1) leaf area per fruit, (2) nutritional status of tree and (3) the water available throughout the growing season. All growers may not be able to apply water to supplement rainfall but all growers can thin. In spite of high labor costs, the effort made to thin the peach crop should pay dividends as shown in the table below. A 3-inch peach has about 3 times the volume of a 2-inch peach. A 2 1/2-inch peach has 2 times the volume of a 2-inch peach. Trees bearing a heavy unthinned crop of peaches produce small-sized low valued fruits. In addition, limb breakage may be excessive which reduces the future bearing capacity of the trees. W. J. Lord.

Number of Peaches per Bushel for Given sizes of Fruit

Diameter of Peach
Peaches in Bushel
2 inch
2 1/8 inch
2 1/4 inch
2 3/8 inch
2 1/2 inch
2 5/8 inch
2 3/4 inch
3 inch