![]() ![]() Pierre and Valley Sunset for first for disease symptoms. Check susceptible cultivars such as Kent, Wendy, St. Monitor for leaf scorch in early spring to assess whether early sprays are needed. Symptoms appear within 7- 9 days after infection and spores are produced within 10 - 14 days. The optimal temperature for germination occurs between 20 and 25☌ (68- 77☏) but germination can occur at temperatures between 5☌ and 30☌ (41- 86☏) with a sufficient wetting period (at least 6- 9 hours). Most infections take place in early spring, or mid-August to late September- when most leaves are young and frequent rains or heavy dews provide good conditions for infection. Leaf scorch can infect strawberry leaves at all stages of development. Inoculum and disease pressure are higher in older plantings because there is more leaf litter and the disease has had to time to build up on the older leaves. Younger leaves tend to be more susceptible to infection than older leaves. Leaf lesions produce conidia throughout the growing season which allows for repeated infections. In Ontario, both conidia and ascospores may be initial sources of leaf scorch in the spring and germinate under wet conditions leading to the infection of new strawberry tissue. The fungus, Diplocarpon earlianum, overwinters in both living and dead strawberry leaves. Leaf edges curl and large areas of the lower leaf surface become discoloured- pink or grey.) There is slight yellowing in purpled areas. Powdery mildew (Powdery mildew produces purple spots that are variable in size, from specks to flecks to larger spots. Leaves gradually turn brown, dry up, and curl at the edges giving them a burned or scorched appearance. These lesions join together and may turn bright red. Leaves develop numerous purplish-brown blotchy lesions. Leaf scorch usually infects leaves and calyces occasionally it infects runners, flowers and fruit. Monitor from mid-August to early October to determine disease pressure for next year. Examine middle-aged leaves during the harvest period to assess whether a protectant spray is needed after renovation. Check susceptible cultivars such as Allstar, Kent and Micmac for first disease symptoms. Symptoms appear within 7- 9 days after infection and spores are produced within 10- 14 days. Leaves eventually turn brown, dry up and curl up at the edges giving a burned or “scorched” appearance.Lesions join together and may turn bright red. ![]() Infected leaves initially appear to have numerous purplish-brown blotches.Infects leaves, runners, flowers, fruit and calyx. ![]()
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