The Cosmic Crisp apple, developed by Washington State University, is known for its crispness, balanced sweet-tart flavor, and extended storage. A cross between Honeycrisp and Enterprise, it inherited desirable traits like Honeycrisp’s texture and Enterprise’s long storage and disease resistance. Its distinctive dark red skin with white lenticels inspired its “Cosmic” name. Understanding its pollination requirements is important for successful fruit production.
The Basics of Apple Pollination
Most apple varieties are not self-fertile, requiring pollen from a different apple variety to produce fruit. This cross-pollination is primarily carried out by insects, with bees being the most significant pollinators. When bees visit apple blossoms, pollen grains adhere to their bodies and are transferred to other flowers, facilitating fertilization. Without effective cross-pollination, apple trees may bloom profusely but yield little to no fruit, or the fruit might be malformed or drop prematurely.
Successful apple pollination relies on compatible apple varieties blooming simultaneously and sufficient pollinator activity.
Cosmic Crisp’s Specific Pollination Requirements
Cosmic Crisp is not self-fertile and requires cross-pollination from another apple variety. Its parent varieties, Honeycrisp and Enterprise, cannot effectively pollinate Cosmic Crisp due to their close genetic relationship and shared genetic markers.
This genetic barrier is governed by S-alleles. Each apple variety has two distinct S-alleles. For successful cross-pollination, the pollen’s S-alleles must not match both S-alleles of the receiving flower. If a pollen grain shares an S-allele, pollen tube growth is halted, preventing fertilization. Cosmic Crisp has S-alleles S5 and S24. Honeycrisp (S2, S24) and Enterprise share S-alleles with Cosmic Crisp, making them unsuitable pollination partners. Therefore, selecting a pollinator with distinct S-alleles is crucial for fruit set.
Identifying Suitable Pollinators
For successful fruit set, select varieties with overlapping bloom times and genetic compatibility. Cosmic Crisp is a mid to late season bloomer, typically in bloom category 4. Other apple varieties blooming in categories 3, 4, or 5 are generally suitable pollinators, such as Gala (bloom group 4).
Late-flowering crabapple varieties are also recommended. Crabapples like Snowdrift and Mt. Everest provide abundant pollen and align well with Cosmic Crisp’s bloom period. Their small fruit size minimizes concerns about unwanted fruit production.
Practical Strategies for Successful Pollination
Orchard planning is important for maximizing Cosmic Crisp yield through proper pollination. Planting multiple compatible apple trees or integrating pollinator varieties within the orchard design is a common strategy. In commercial settings, planting a row of pollinizer trees for every four rows of the main variety ensures adequate cross-pollination. For smaller gardens, combination apple trees with multiple varieties grafted onto one rootstock can provide internal cross-pollination.
Pollinator trees should be planted within 50 to 100 feet of Cosmic Crisp trees for efficient pollen transfer by bees and other insects. Protecting pollinator populations is also important. Avoid applying pesticides, especially insecticides, during bloom time when bees are most active. Providing alternative flowering plants and nesting habitats near the orchard can further support healthy pollinator populations.