Door County Report, September 18, 2019
Apple harvest has begun! Maturity levels are running 6-8 days later than normal due to cool, wet weather. We are currently harvesting Murray, Zestar, and spot picking MacIntosh. There are also some cider apple varieties nearing maturity.
Apple maturity at PARS for apple collected on Sept 16, 2019
| Variety | Firmness lbs (range) | Starch (range) | Brix | Color% |
| Blondee | 24.6 | 1.0 | 9.0 | 15% |
| Cortland | 17.2 | 1.0 | 11.5 | 50% |
| Honeycrisp | 16.3 | 1.9 | 10.9 | 45% |
| Mollies Delicious | 15.5 | 5.5 | 12.6 | 65% |
| Royal Cortland | 15.6 | 1.0 | 11.6 | 65% |
| Zestar | 12.0 | 7.2 | 12.0 | 90% |
Brix readings are a guide for target sugar levels in fruit. The higher the better, but from year to year there’s quite a bit of variation. Light crops will tend to have higher brix levels, and heavy crops will be on the low end. Honeycrisp are expected to have higher brix. Brix can be measured with a portable refractometer which is available online.
Brix readings on Honeycrisp & other varieties
| Brix Guide | Low | Fair | Good | Excellent |
| All varieties | < than 11 | 11 | 12 | 13 |
| Honeycrisp | < than 12 | 12 | 13 | > than 14 |
Apple maturity reports will be published weekly on the Peninsular Agricultural Research Station website.
Insect and Disease Control
As we approach harvest, make sure to double check the preharvest interval for any product you might use!
Apple
Disease Pressure – A late season apple scab spray may be needed in blocks with active apple scab lesions due to the high amount of fog/mist we’ve had over the past week.
Insect Pressure – There is moderate apple maggot pressure in all scouted orchards and high pressure in blocks adjacent to abandoned orchards. Codling moth pressure is light as we are at the end of the second generation flight. There is still a bit more pressure farther north at this time. Adult plum cuculio beetles have been caught in two unsprayed orchards this past week. No brown marmorated stink bugs have been caught this year, but other types of stink bugs are active. There appears to be some stink bug or tarnished plant bug damage showing up on fruit in some blocks with heavy insect pressure. The feeding from both species looks very similar to bitterpit. If you are noticing higher amounts of what you think is bitterpit, it is worth checking the fruit closely to evaluate whether it is actually insect feeding damage.
When testing for apple maturity, it is important not to go by color alone this year, because color is developing faster than the apples are maturing. Make sure to use a variety of tests so that you ensure your apples are harvested at the optimal time.
Cherry
The cherry season is basically complete. Any last hedging should be finished up this week so that the branches can heal over before the winter. Fall is also a good time to apply white latex paint to trunks to prevent southwest winter injury. Those wounds give borer insects an entry point which leads to early tree decline as larvae burrow under the bark.
Grape
These are current wine grape varieties being tested at PARS.
Grape Variety Quality 9/16/2019
| Location | Cultivar | Brix | pH |
| Block 53 | LaCrescent | 13.6 | 2.85 |
| Block 53 | Frontenac | 13.1 | 2.82 |
| Block 53 | Marquette | 15.4 | 2.82 |
| Block 51 | Marquette | 15.6 | 2.92 |