2020’s unusual weather continues to provide unwelcome surprises. We are now seeing lots of apples with cracks. This can happen to pears and other fruit as well. Shallow cracks often heal but the fruit develops scars and the fruit is deformed. Decay may occur in fruit with deeper cracks, especially near harvest, as increased insect activity and secondary pathogens are more likely. Severely cracked fruit will likely not mature or be worth eating.
It’s common to see the same symptoms appear on garden vegetable such as tomatoes, cucumbers and peppers without regular watering.
What Causes Cracked Apples
Fruit split can be confused with disease, but it is actually caused by an irregular supply of water. The cracks form when heavy rain and high humidity follow a prolonged dry spell, stimulating a rapid swelling of the fruit. The skin is not able to expand enough to accommodate the abundance of moisture and is stretched to a breaking point. The susceptibility of fruit to splitting varies with the apple cultivars, as well as by location and microclimates.
Most Susceptible Cultivars
The apple cultivars most susceptible to cracking are the popular Fuji, Gala, and Golden Delicious, and the lesser known Stayman, Wealthy and York.
Other Contributing Factors
When a fruit tree has health issues that result in less foliage and fruit, the smaller surface area reduces its ability for evapotranspiration, leading to fruit cracks. Stressed trees that are suffering from poor soil health, lack of moisture, insect or disease issues will not produce abundant foliage and strong flower buds. The fruit set is then low and excessive fruit drop is likely.
• Very late and hard pruning can affect normal growth of foliage.
• Sections infected with apple scab are not contributing the surface area of the tree.
• Trees with weak root systems cannot access water and nutrients as readily and are less resilient when faced with environmental stress.
What Can Be Done
Fruit cracking can be alleviated by giving the tree a steady supply of water during dry and hot stretches of weather. This is of course much easier said than done, so most of our apple trees remain at the mercy of Mother Nature. Additionally, ensuring the overall health of the tree through proper pruning, insect and disease control and improving soil health will help increase its ability to withstand environmental stressors.
Definitions
Cultivar vs Variety
A cultivar is a plant that is produced and maintained by horticulturists but does not produce true to seed. A variety is a group of plants within a species that has one or more distinguishing characteristics and usually produces true to seed.
True to Seed
True to seed, or growing true, refers to plants whose seed will yield the same type of plant as the original plant.
Evapotranspiration
Evapotranspiration is a combination of evaporation and transpiration. Evaporation is the physical movement of water into the air. Transpiration is the biological process of plants releasing water vapor through leaves. This water was previously pulled up by the roots from the soil.