By Blake Jackson
Pollination is a critical part of a tree’s reproductive cycle, relying on several biological and environmental factors such as cultivar compatibility, overlapping bloom periods, insect activity, and suitable weather. A deficiency in any of these elements can reduce fruit set and crop quality.
While bees are the primary pollinators for most tree fruit crops, some flies, beetles, and thrips may contribute to a lesser degree. Honey bees are commonly used due to their ease of management and mobility, while mason bees and over 120 species of wild bees also play a significant role.
Cold temperatures during bloom can hinder pollination, as pollen may not germinate below 5°C, and pollen tube growth slows below 10.55°C. Even if bees are active, insufficient pollen tube growth before embryo sac deterioration can prevent fertilization.
The Effective Pollination Period (EPP) measures the time between pollen tube growth and ovule receptivity, typically 2-4 days, varying by cultivar. Longer EPPs increase the chance of successful fertilization.
All apple cultivars require cross-pollination to achieve commercial yields. Self-fruitfulness varies; for instance, Golden Delicious is partially self-fruitful, whereas Red Delicious is not.
Triploid varieties cannot pollinate others, and closely related varieties may be incompatible. Successful cross-pollination requires overlapping bloom, viable pollen, proximity of pollinizers, active bees, and minimal competing blossoms.
Pollinizer placement enhances pollination. Alternating pollinizer rows between main cultivar rows, or planting pollinizers every third row for less self-fruitful varieties, improves pollen distribution. Ornamental crabapples, which bloom annually, can also serve as effective pollinizers, increasing cross-pollination without introducing less profitable cultivars.
Recommended crabapple cultivars include Manchurian, Pioneer Scarlet, Rosedale, Golden Hornet, Snowdrift, and Simpson 10-35. Using multiple crabapple cultivars with staggered bloom periods ensures consistent pollination, even in cold or biennial-bearing years.
Proper pollinator management and strategic pollinizer placement lead to higher yields, better fruit size, and improved overall orchard productivity.
Photo Credit: gettyimages-richard-7
Categories: Pennsylvania, General