UMass Healthy Fruit Volume 8, No. San Jose Scale is a somewhat overlooked pest that can result in reduced orchard productivity and tree death.
Scale literally sucks the juice out of the host plant, including apples and stone fruit.
Although generally controlled by spring oil applications, it may become more prevalent during periods of mild winter weather and where pesticide programs become 'softer'. Look for slow, otherwise unexplained, dye-back of shoots and limbs as a sign of scale infestation. Red 'stippling' of fruit at harvest is also a good sign of scale infestation. In the past two weeks, we have seen no indication that any additional late-emerging plum curculios have moved into orchard blocks from overwintering sites. In a few cases, these late-arriving PCs have enjoyed periods of optimal egglaying conditions on virtually untreated trees.