The Control of Apple and Pear scab by Sulphur Sprays
My James Grieve has for the past 3 years suffered some scab on the leaves. This wouldn’t be a problem, except for the fact that it can severely mark the fruit in due course and in wet seasons. By resorting to a regular spray of sulphur, I have managed to prevent it reaching and marking the fruit. Sulphur is a basic chemical, so relatively harmless to the environment. The weather conditions earlier this year in the east were very favourable for scab spores, but luckily this last week’s dryer conditions has improved the situation tremendously. In the west of Scotland it is a problem most years. Powdery mildew has also been prevalent on many apples this year also and sulphur will reduce this also. It attacks the new young leaves and slows down the growth of trees for many months.
I use 5.6 mls in 10 litres of litres water and spray the leaves every 10 to 14 days if I can. I start at the ‘pink bud’ stage and continue until the end of extension growth, around about mid- July. It is essential to achieve good coverage of all parts of the tree, especially the growing points – they will have the appearance of a smattering of snow after spraying!
Certain varieties of fruit trees and bushes may be damaged by sulphur sprays. In the old books they called this ‘sulphur shyness’. The following are reportedly susceptible to leaf damage: Beauty of Bath, Belle de Boskoop, Cox’s Orange Pippin, Lane’s Prince Albert, Lord Derby, Newton Wonder, Rival, Stirling Castle, and Doyenne du Comice.
My Hawthornden seems a touch damaged, and possibly my George Cave, but since the first few applications, I have restricted my sprays to Worcester Pearmain and James Grieve only, the only two in my garden showing any significant scab symptoms.The Boskoop seems to be ok in my garden, and none of the pears show any damage.
I have seen scab on Scrumptious this week, and many new so-called resistant varieties usually succomb after a few years in the field unfortunately. Knowing when spores are in the air is how the professional’s are able to time their spraying; we may rely on regular pruning and good open sunny sites as the best prevention!