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First Symptoms of Apple Blotch Disease Visible on Leaves in Winchester VA

On 26 July we visited a classic training system orchard in south part of Winchester, VA, with trees of apple cv. 'Ginger Gold' and detected symptoms of Apple Blotch Disease (ABD), also known as Marssonina Leaf Blotch (MLB). The symptoms were found on the lower scaffolds in the canopy and are visible in Figure 1 . This disease primarily expresses on apple leaves and is caused by a pathogenic fungus Diplocarpon coronariae . Even though we recently experienced dry weather periods in the Shenandoah Valley, e xcessive rains we received in May and June 2021 favored the development of ABD. Leaf symptoms express as grey to brown large round spots (blotches) that can merge. This leads to leaf yellowing. Figure 1. Apple Blotch Disease (aka Marssonina Leaf Blotch) on apple cultivar 'Ginger Gold' in Winchester, VA. If effective fungicides are not applied timely, continued infections by D. coronariae can occur during summer and until the leaves are present on the trees.

More Rain = More Apple Bitter Rot: Late Maturing Apple Cultivars Need Continued Fungicide Protection up Until Harvest (!)

Bitter rot incidence is high in some Virginia and West Virginia apple orchards as hot summer days with drought mid- summer preceded rains in August and September. Bitter rot emerged at an increasing rate where fungicide was stopped in June or July or coverage until harvest was less frequent then necessary after many small rain events that in the end summed up to 2 inches of rain or more (Fig. 1). In addition, we had a severe 3 inches of rain brought in by the hurricane Ida that were highly favorable for infections by bitter rot fungi from genus Colletotrichum . If you spray every row (full orchard coverage), your fungicide cover spray is worth 14 days or 2 inches of rain, whichever comes first. Under this spray scenario, if you do not get rain for 14 days, you can extend the spray interval to 21 days, under the condition that you do not get rain during the 7 additional days. However, if you spray every second row every 14 days ( alternate row middle) , f ruit rots will be or have

VIRGINIA TREE FRUIT DISEASE UPDATES

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