Dealing with apples and pears with fungal disease
Q Why are the apples and pears on my fruit trees all scabby and what should I do to avoid this next year? Nelly Tully, Cooga, Ireland A The fruits you describe are suffering from a fungal disease aptly called apple scab, though it also affects pears.
T he symptoms begin in spring, with olive green or brownish spots and blotches appearing on leaves, coupled with a velvety appearance while spores are being released. Later, the patches turn darker and sometime crack. Leaves are likely to fall early. Fruits are affected too and, to be honest, many domestic fruit trees across the country are infected with scab to some degree. Most of us are able to carry out good preventative care and continue to harvest decent fruit.
Trouble starts when severe blemishes render a large proportion of the crop almost inedible. Black scabs on the skin prevent it from expanding as the fruit grows, causing splits and fissures through which infections like rots can enter. Fruits become badly distorted and once damaged, won’t store.
Look hard and you’ll notice scabby patches on young stems and these, along with infected fallen leaves are where scab, or Venturia inaequalis, overwinters. Airborne spores are produced in spring, which infect young leaves. Encouraged by wet, overcast weather and congested growth, more spores develop and spread.
In older books, much was written on the use of fungicides no longer available. Even if they were, few of us wish to douse our gardens in them nowadays. The solution lies in preventative measures, or even grubbing out susceptible trees and replacing them with resistant varieties.
This seems harsh, but we took out several scab-afflicted trees soon after moving into our current garden and never regretted it.
Apple and pear varieties are quite localised in their origin and it pays to choose those that have a history of growing well in your area, especially on the wetter, western side of the country.
Two of the worst affected pears, showing typical black patches that stop the skin from stretching A pear tree in our garden suffers from scab, but most fruits are edible and delicious.