ISSUE 3 – Sept 18, 2007
Summaries of apple maturity for
Jonathan (7 sites sampled, 3rd week) Fruit firmness averaged 16.9 (range 15.1 to 19) about one lb less than last week. Starch removal index of 5 compared to 4 for last week. Brix average of 13.5 is about the same as last week. Some of the Jonathan blocks have starch indices too high for successful longterm CA storage. Growers are actively harvesting of Jonathans destined for processing. Background skin color for some strains in some blocks still may be too green for some fresh markets. Growers should move aggressively on this variety, based on firmness and starch readings.
CA longterm firmness Firmness ---- Starch removal -----------
Guidelines: Excellent Acceptable short term immature mature overmature
Jonathan > 16 lb 16 to 15 lb < 15 < 3.5 3.5 to 5.5 > 5.5
Empire no more sampling, most harvested in areas
Honeycrisp -- still spot picking in area, most are harvested.
Jonagold (5 sample sites, 3rd week) firmness this week averaging 18 compared to 18.3 for last week. Starch removal index readings average 4.7 compared to 3.7 for last week. Average brix this week is 13.5 compared to 13 for last week. Good firmness will still allow delay of harvest to wait for better background color if needed for some sites. Starch removal indices in the mature range for most sites indicates that harvest should be underway if color permits.
CA longterm firmness Firmness ---- Starch removal -----------
Guidelines: Excellent Acceptable short term immature mature overmature
Jonagold > 16 lb 16 to 15 lb < 15 < 3.5 3.5 to 5.5 > 5.5
Golden Delicious (9 samples, 3rd week). Firmness this week averages 17.5 compared to 18.4 for last week. The starch index for this week averaged 2.6 compared to 2.0 for last week. Brix averaged 14.0, about one degree higher than last week. Some blocks have dropped into the mature zone for starch conversion and with firmness below 17 lb for some blocks--growers should consider harvesting for CA storage.
CA longterm firmness Firmness ---- Starch removal -----------
Guidelines: Excellent Acceptable short term immature mature overmature
G. Delicious > 17 lb 17 to 16 lb < 15 < 3.0 3.0 to 5.0 > 5.0
Red Delicious (5 samples, 2nd week). Firmness averaged 16.9, almost 1 lb less than last week. Starch conversion index is 3.6 compared to last weeks 2.9. Brix has increased slightly over last week and now is 10.3. All samples tested are already below the 18 lb level for excellent firmness and have starch conversion firmly in the mature zone. Harvest can proceed for orchards with sufficient skin color. This variety is relatively advanced this year. Harvest is underway for longer term CA storage
CA longterm firmness Firmness ---- Starch removal -----------
Guidelines: Excellent Acceptable mid term immature mature overmature
Red Delicious > 18 lb 18 to 17 lb 17 to 16 lb < 2.5 2.5 to 5.0 > 5.0
IdaRed (4 samples, 1st week). Firmness averaged 16.8, starch conversion index is 2.8, with brix of 11.4. Some harvest for CA storage is underway, as well as some for cold storage for more immediate processing. Firmness is still very good and harvest can wait for better starch conversion.
CA longterm firmness Firmness ---- Starch removal -----------
Guidelines: Excellent Acceptable mid term immature mature overmature
IdaRed > 16 lb 15 to 16 lb 14 to 15 lb < 3.5 3.5 to 6.0 > 6.0
Current and past years
summaries can be found on the SW Michigan Research and
This report and project is made possible by the support of our sponsors which
include Gerber Products Company, Valent