Control
In affected orchards, new infections can be reduced by removing leaf litter and trimmings containing infected tissue from the orchard and incinerating them. This will reduce the amount of new ascospores released in the spring. Additionally, scab lesions on woody tissue can be excised from the tree if possible and similarly destroyed.
Chemical controls can include a variety of compounds. Benzimidazole fungicides (e.g., Benlate ) work well but resistance can arise quickly; Similarly, a number of chemical classes including sterol inhibitors such as Nova 40, and strobilurins such as Flint among others, were used extensively but are slowly being phased out because of resistance problems.
Contact fungicides not prone to resistance such as Captan are viable choices. Copper or Bordeaux mixture are traditional controls but are less effective than chemical fungicides and can cause russeting of the fruit. Wettable sulfur also provides some control. The timing of application and concentration varies between compounds.
15 genes have been found in apple cultivars that confer resistance against apple scab. Researchers hope to use cisgenic techniques to introduce these genes into commercial cultivars and therefore create new resistant cultivars. This can be done through conventional breeding but would take over 50 years to achieve.
Read more about this topic: Apple Scab
Famous quotes containing the word control:
“The glance is natural magic. The mysterious communication established across a house between two entire strangers, moves all the springs of wonder. The communication by the glance is in the greatest part not subject to the control of the will. It is the bodily symbol of identity with nature. We look into the eyes to know if this other form is another self, and the eyes will not lie, but make a faithful confession what inhabitant is there.”
—Ralph Waldo Emerson (1803–1882)
“Grown-up people do very little and say a great deal.... Toddlers say very little and do a great deal.... With a toddler you cannot explain, you have to show. You cannot send, you have to take. You cannot control with words, you have to use your body.”
—Penelope Leach (20th century)
“There has been something crude and heartless and unfeeling in our haste to succeed and be great. Our thought has been “Let every man look out for himself, let every generation look out for itself,” while we reared giant machinery which made it impossible that any but those who stood at the levers of control should have any chance to look out for themselves.”
—Woodrow Wilson (1856–1924)