It’s common for newly planted and young apple trees to set fruit, but allowing these young trees to bear fruit can hinder their growth and the goal of filling in space within the first three years. To ensure healthy tree development, it’s essential to remove blossoms and fruitlets from young apple trees. Here are several effective methods to achieve this:

1. Lime Sulfur (LS) Application at Bloom

Lime Sulfur can be used to reduce fruit set in young or newly planted orchards. Here’s how to apply it:

– LS Alone: Use at 4-10% (v/v).

– LS with Oil: Use at 1.5-2% (v/v) with the following oil options:

• Fish oil at 2% (v/v)
• Dormant petroleum oil at 1%
• Summer oil at 1-1.5% (v/v)

2. Ammonium Thiosulfate (ATS) Application

Another method to remove blossoms during bloom is using ATS:

– ATS: Apply at 2 gallons per 100 gallons of water, at 100 gallons per acre. Do not mix with oil.

While LS is generally more effective than ATS, LS temporarily inhibits photosynthesis, which can be harsh on young trees with less foliage. Additionally, LS can cause apple leaf burn.

Important Tips:

– Avoid using LS and ATS if temperatures are forecasted to exceed 80°F within 24 hours.

– Do not spray under slow drying conditions (low light, high humidity) to reduce the risk of injury.

– Tender foliage, grown under cool, cloudy, damp conditions, is more likely to show symptoms of injury.

3. Sevin + MaxCel or NAA Applications at Petal Fall

At petal fall, applying Sevin combined with MaxCel or NAA can effectively thin fruitlets with minimal stress to young trees:

– Sevin + MaxCel: Use 2 pints of Sevin plus 4 pints of MaxCel per 100 gallons. Apply again when fruitlets are 8-10 mm in size.

– Sevin + NAA: Use 2 pints of Sevin plus 15 ppm NAA. Apply first at petal fall and then again when fruitlets are 8-10 mm.

Note: NAA is a more aggressive thinner than MaxCel and Sevin, so avoid using it if high temperatures (over 85°F) are forecasted, as this can cause some leaf drop.

4. Hand Thinning

Hand thinning is a reliable alternative, especially if there are not many blossoms. When hand thinning, ensure to remove only the flowers and not the actively growing terminal shoots.

By implementing these strategies, apple growers can effectively manage fruit set in young trees, promoting healthier growth and better space utilization. Always consider weather conditions and tree health when choosing and applying thinning methods to avoid potential damage and ensure the best outcomes for your orchard.

This article was posted in Apples and tagged Amaya Atucha, Apples, fruit set, managing fruit set.