Advice

RHS Help & Advice

Cherry fruit drop

A common problem affecting yields of cherries grown in cool-temperate climates

The problem

Some fruit trees shed surplus fruit that they cannot support (for example apples, during ‘June drop’). Many members of the Prunus group, such as apricots and almonds, have a similar fruit drop - sometimes to excess. In the UK the most common fruit to suffer crop failure by fruit drop is sweet cherry. This is referred to as cherry run off.

The extent of cherry run off varies between years. In 2000 in the UK, as much as 90 percent of fruit initially set on sweet cherry trees was lost before full maturity. Severity of fruit drop varies between geographical location (cherries in northern areas such as the UK suffer much worse than those grown in the south of Europe) and within species (some cherry rootstocks and cultivars may be less affected).

Possible causes

Research suggests that in sweet cherry a combination of climatic factors coincides with heavier fruit drop. These include poor weather (low light intensity) during blossom and low temperatures in the early stages of fruit development. Furthermore, fruit yields are lower following wet and cold autumns.

When leaves send insufficient photosynthetic products (food) to the fruit, this causes an imbalance in the hormones within fruit resulting in increased fruit drop.

Prevention

Any measure that maximises light to the leaves increasing the photosynthetic rate is likely to minimise fruit drop.

Little can be done about the weather, but pruning trees to give a more open canopy and using light-reflective mulches such as pale woodchip beneath the tree should help.

Alternatively, grow against a sunny wall or by a light-coloured path. Thinning fruit will help maintain the balance of supporting foliage.

Tijana Blanusa