Pest(s) | | Materials | Rate per Acre | Comments |
5.2.13 POSTHARVEST |
Sour rot | Recent research has shown that disease development can be reduced through a combination of insecticide sprays to control Drosophila fly populations (see information under minor and special insect pests for labeled materials) and registered broad-spectrum sterilants (e.g., Oxidate) to limit microbial populations on the berries. Some data suggest that the insecticide component may be the more important of the two, if only one of them is to be applied. This program is most effective if started around 15°Brix, about the time that berries become susceptible and before symptoms first develop, but it also can restrict further spread if initiated soon after the disease is noticed through scouting activities. Limiting various causes of injury will also greatly reduce sour rot development. Open canopies and leaf removal around clusters, which allow them to dry once rains have stopped, can lower disease severity significantly. |
In some years and on some varieties, downy mildew may cause defoliation after harvest but well before frost; this is also possible with powdery mildew, but rapid spread of this disease is likely late in the season. Premature defoliation, especially in early harvested varieties or winter-tender Vitis vinifera, predisposes the vines to winter injury and reduces bud survival the following spring. Good control of downy and powdery mildews through August greatly reduces the need for postharvest treatments. Also note that new, young foliage is most susceptible to infection and most likely to benefit from continued protection. To delay the development of resistance, it is recommended that resistance-prone fungicides not be used during the postharvest period. |
Downy mildew | | Copper compounds (several formulations) | see label, rates vary | Copper may cause injury if applied during cool temperatures or under slow drying conditions. |
| | Captan 4L | 2 qt | |
| | or Captan 50WP | 4 lb | |
| | or Captan 80 WDG | 2.5 lb | |
| | or Captan Gold 4L | 1-2 qt | |
| | or Captan Gold 80WDG | 1.25-2.5 lb | |
| OR | *NYDithane DF | 4 lb | |
| | or Dithane M45 | | |
| | or Manzate Pro-Stick 75DF | | |
| | or Penncozeb 75DF | | |
| OR | *NYDithane F-45 | 3.2 qt. | |
| or *NYManzate Max 4F | | |
| OR | Howler | 2.5-7.5 lbs | |
Powdery mildew | | Sulfur compounds (several formulations) | read the label | |
| OR | JMS Stylet Oil | 1-2% conc., read the label | Sufficient water to provide thorough spray coverage and a final volume of at least 1 gal of JMS Stylet Oil per acre are essential for good performance by this material. |
| OR | Purespray Green | 1-2% conc. | |
| OR | Regalia | 1-4 qts (see label) | Regalia is a biopesticide that has provided fair to very good control of powdery mildew in NY trials, depending on disease pressure. It is likely to work best on less susceptible varieties or at times of year when pressure is low. Different rates are recommended depending on whether it is used alone or in a tank mix. Because Regalia requires 48 hours to activate plant defenses, applications need to start before infection. This product could be included in an organic spray program or in rotation before or after the critical powdery mildew control window (immediate prebloom and post bloom) to slow the development of resistance to other products. Regalia should not be relied on for powdery mildew control during immediate prebloom and post bloom applications. |
| OR | ProBlad Verde | 18.1-45.7 fl oz | ProBlad Verde is a biopesticide that has provided fair to good control of powdery mildew in NY and PA trials. ProBlad Verde is OMRI listed and can be included in an organic spray program or in rotation before or after the critical powdery mildew control window (immediate prebloom and post bloom) to slow the development of resistance to other products. ProBlad Verde should not be relied on for conventional powdery mildew control during this critical window. No more than 5 applications can be made during the season, and ProBlad Verde may be applied no more than twice before alternating with a product that has a different mode of action. |
| | | |
| OR | Howler | 2.5-7.5 lbs | |
| OR | Romeo | 0.23 lbs | |
| OR | Stargus | 0.5-4.0 qts | Stargus has shown to be more effective when tank mixed with Regalia. |
KEY FOR SECTION 5.2: |
* Federal restricted-use pesticide*NY Restricted-use pesticide in New York State |
† Not for use in Nassau/Suffolk Counties.^ Not registered for use in New York State at press time |