Green Tip in Apples – Are You Prepared?

Signs of green tissue are showing this week in the southwest regions of the province from Harrow, Simcoe and Niagara. If dormant applications have not gone on yet, now is the time to get those trees covered for early season pest management. Consider the following:

Fight fire blight with dormant copper

• After the bad year we had last year for fire blight across the province, applying copper from silver tip to 1/4″ green this year is even more important.
• May have an impact on any early apple scab activity if overwintering inoculum is present. Note: this should not replace your first scab cover, especially if you were chasing scab last year.
• If fire blight was a problem in your orchard OR IN YOUR NEIGHBOURHOOD, consider applying copper to all your blocks, including young trees. Getting on top of management early will save you from any surprises later.
• Depending on the copper product, the later into the season you make an application, the greater the risk of phytotoxicity and fruit russeting.

Avoid summer rescue sprays with dormant/delayed-dormant oil

• If scale damage was found at harvest last year, management is critical to prevent even higher losses this year. Dormant oil is the first line of defense.
• While the optimal timing for scale control is before bud break, a delayed-dormant oil application (2% sol.) from green tip to tight cluster will still have some efficacy while also targeting European red mites.
• Since oil works by suffocation of immature scale and mite eggs, getting this spray on as soon as you can and with thorough coverage will maximize efficacy.
• There are often concerns of bark damage caused by the use of oil. Like many other products, there is a possibility of damage if used improperly. Be sure to avoid the following situations to reduce the risk of injury:
  • Do not apply oil if frost is forecast 48 hour before or after planned application.
  • Allow at least 10-14 days between oil and the use of captan or sulphur products. Oil can enhance penetrant activity of these products, resulting in phytotoxicity.
  • Do not apply oil during periods of slow drying conditions that may lead to burning of sensitive tissues.
  • Red Delicious, Empire, Mutsu and Ambrosia can be particularly sensitive to bark damage if applied in conditions listed above.

Reduce scab inoculum before primary infection

• The primary scab infection period has begun in some regions south of the border (see Penn State disease update), which means Ontario is not far behind. Leaves are susceptible to infection as soon as green tissue is present.
• If you were chasing scab in your orchard and did not do any sanitation practices (urea, flail mowing) in the fall, the inoculum levels are likely high enough that mature spores could be released with early wetting events.
• A good way to reduce the scab pressure you’re starting out with in the orchard this season is to apply urea fertilizer at 45 kg/ha (mixed with 1,000 L water/ha) and/or shred fallen leaves with a flail mower. Both practices facilitate the breakdown of leaf litter.