Disease-Resistant Apple Cultivars

There are more than 100 modern apple cultivars, and several dozen antique varieties, that have been selected in part for their disease resistance. They offer a broad range of flavors, appearance, taste profiles, storage potential, and harvest dates from mid-summer to early winter. This disease resistance was achieved by hybridization with other apple species with resistance to significant diseases, primarily apple scab (Venturia inaequalis), through natural selection or controlled breeding. Malus floribunda, also known as Japanese flowering crabapple,  …

Pre-harvest Drop

Apples sometimes drop to the ground before they reach the desired harvest maturity. This pre-harvest fruit drop can cause significant losses in apple orchards. As apples mature, an abscission layer of specialized cells naturally forms between the apple stem and the fruit spur to which it is attached. The abscission layer allows the apple to be released from the tree without causing damage to the tree. However, apples may fall off the tree before the ideal harvest maturity has been …

Parentage of Apple Cultivars

 

Nearly all apple cultivars have two parents – just like humans!  Apples have a genetic system that generally prohibits self-fertilization.  This self-incompatibility system is a way of insuring that each apple seed will be a hybrid between the maternal (seed) parent and a paternal (pollen) parent. The self-incompatibilty system is also the reason why two or more cultivars must be planted in an orchard to achieve fruit production through insect-vectored movement of pollen from one cultivar to the other.

Chance

Disease Management in Apple Trees and Fruit

Bitter Rot of Apple

Bitter rot is a fungus disease that causes fruit rot during the summer and preharvest period. The bitter rot fungi are almost worldwide in distribution and cause an especially important economic disease in the southern areas of the United States. Outbreaks can occur rapidly, and losses can be severe, especially under prolonged warm, wet weather. Several host species can be affected. On peach and nectarine, the same fungus causes a disease known as anthracnose, and on grape it causes ripe …

Effect of Wind on Apple Trees

Strong wind, especially wind associated with tropical storms that saturate the soil, can cause fruit trees to lean and sometimes be totally uprooted. Due to small and brittle root systems, dwarfing rootstocks tend to be prone to wind damage.

Susceptibility to wind damage appears to be related to the combination of rootstock and scion cultivar. Some brittle cultivars, such as ‘Gala’ and ‘Golden Delicious’, when propagated on brittle rootstocks, such as G.30 or M.26, may snap at the bud union. …