Back to top

Healthy Fruit 2010 Vol. 18:18

Sep 7, 2010

Orchard Radar preliminary McIntosh harvest date forecasts (for Belchertown)

Begin measuring actual McIntosh starch-iodine index no later than Wednesday, August 18

The Michigan formula estimate for standard (i.e. non-spur) McIntosh starch index 4.0 and beginning of optimum McIntosh harvest for CA storage is Wednesday, August 25. Estimate adjusted to lessen influence of unusual bloom date is Tuesday, August 31

Cornell Bulletin 221 provides formulas for different locations to estimate date when non-spur McIntosh reach starch index 6.0 and the end of optimum harvest for CA storage. Using the Hudson Valley formula, the estimated end of McIntosh CA harvest for Belchertown MA is Wednesday, September 15!!!

The way I see it

This week's Healthy Fruit is dedicated to harvest maturity. It's a mixed bag out there and I am a little baffled, but the bottom line is you should be picking hard most everything that is even close to ready right now. This includes Macs, Honeycrisp, and Gala (if you have not already done so). My overall impression is stressed trees are dropping fruit, and the rain we got last week from Earl in the east may help. It is getting increasingly dry (and warm across-State) again in the west, so I suspect drop will contine to be a problem. ReTain already applied to Macs seems to be holding fruit on the trees, however, that may end soon as ReTain-treated Macs are showing fairly high starch-iodine readings. Don't let up on picking Macs and hope for some cooler weather again soon for better color development. It's not too late (but getting there) to apply ReTain to Macoun and Empire if you have not already done so. As soon as Macs are close to done picking then you can start Cortland, Empire, and Macoun. JC

Apple maturity test results

In table-form below are results of maturity testing from apples picked at the UMass Cold Spring Orchard in Belchertown. Mostly they are in-line with harvest maturity being about a week ahead of the long-term average.

date Cultivar pre-harvest drop fruit diameter inches color % red firmness lbs soluble solids starch index
9/6/2010 Lindamac McIntosh nil 3.0 85 14.8 11.3 4.8 (4-6)
9/6/2010 Silken nil 3.0 NA 16 14.4 5.8
9/7/2010 Snappy Mac some 3.2 85 14.7 11.6 5.2 (4.5-6.5)
9/7/2010 Blondee few 3.0 NA 18.3 15.2 6.5 (4.5-7)
9/7/2010 Golden Supreme nil, but prone 3.2 10 17 12 4.3 (2-7)
9/7/2010 Rising Sun Fuji none 2.9 45 14.6 11.6 5.8 (4.5-6.5)
9/7/2010 Redcort Cortland nil 3.2 50 16.5 11.4 2
9/7/2010 Macoun few (push-off?) 3.0 50 dull 17.8 11.8 2
9/7/2010 Tome Empire none 2.8 80 19.4 11.7 3

All harvested at UMass Cold Spring Orchard, Belchertown.

Individual cultivar comments:

Lindamac were 95% picked but color did not seem to be as good this year as it has in the past -- the heat we had last week may have actually reversed color development somewhat. There was virtually no drop on these irrigated, 9th-leaf dwarf trees. Extrapolated yield per acrea, assuming 4 ft. by 14 ft. spacing was just over 1,000 bushels per acre.

Silken is an extemely attractive yellow apple with delicate skin and flesh. Mild but very pleasing eating. Could be a sure thing for farmers markets and pick-your-own orchards -- appearance and taste will sell it. Short season. Some water core observed. Fully picked today (9/7) from 4th leaf trees planted to tall-spindle (3 ft. by 12 ft.). Extrapolated yield off 200 trees was 480 bushels per acre.

Snappy Mac is a highly-colored red strain of Rogers Red McIntosh. Very nice McIntosh fully ready to pick today. No ReTain, some drop observed. All picked today from a replicated systems trial planted in 2006. Extrapolated yield for: vertical-axis M.26 orchard = 600 bushels per acre; central leader MM.106 orchard = 400 bushels per acre. Tall-spindle B.9 Rogers Red McIntosh will be picked early next week while waiting for color development.

Blondee is a newer apple similar to Gala in growth habit and (maybe) flavor. Purported to store very well. Attractive and can be productive but tendency to be biennial. Should be picked with Gala, hence a week ago. These apples were over-mature with stem-end cracking.

Golden Supreme can be an extremely attractive, yellow apple with a pink-orange blush on some, however, it is difficult to grow, biennial, and prone to pre-harvest drop (extemeley uneven ripening). Start spot-picking as soon as you see any drop. These apples are ready for 1st-pick.

Rising Sun Fuji is an early Fuji, however, these are not ready to pick yet based on flavor and sugars (soluble solids). These trees are easily over-cropped and quality will be affected. Wait at least another week to pick.

Cortland, Macoun and Empire are NOT ready to harvest. Wait until next week, pick Macs and Honeycrisp first.

Preliminary 'as-we-go' data from ReTain+NAA experiment

What follows are some preliminary results from a ReTain+NAA stop-drop experiment being done this year at the UMass Cold Spring Orchard in Belchertown, MA by Dr. Duane Greene. The objective of this experiment is to see if the addition of NAA to ReTain could improve the drop control capability of ReTain and to determine if the addition of NAA to ReTain had any influence on advance ripening, reducing flesh firmness or reducing postharvest life.

treatment drops % climacteric firmness soluble solids starch index
control 156 50 13.8 12.4 5.9
ReTain 13 2 14.3 11.6 5.5
ReTain+ NAA 10 ppm 8 0 14.2 11.2 5.5
ReTain+ NAA 20 ppm 7 4 14.6 11.8 5.6
  • ReTain and ReTain+NAA applied at full rate 2-3 weeks before harvest (August 18) to mature, dwarf McIntosh apple trees with a heavy crop (see picture). No irrigation.
  • drops equals accumulated dropped apples (per tree) through September 7
  • % climacteric equals % fruit with internal ethylene concentration >1 ppm
  • firmness, soluble solids and starch index measured September 7

Comments: To this point there has been no influence of NAA at advancing any parameter of ripening. Mostly what you see now is the fact Retain and ReTain+NAA are preventing McIntosh drop compared to the control. Other fruit measurements are marginally different at this point, however the important thing is ReTain and ReTain+NAA timing and application rates are holding apples on the tree. Last year there were no effects of NAA on ripening, firmness or storage potential and so far this result appears to be true this year.

Incidentally the timing for the ReTain+NAA applications appears to be good in retrospect. It requires about 10 to 14 days for the drop control effect of ReTain to start. Drop on the checks started about 2.5 weeks after ReTain application.We expect to continue to collect data for several more weeks until the apples have all fallen from the trees.

Useful links

UMass Extension Fruit Program

Scaffolds Fruit Journal

Follow me on Twitter and Facebook