May 19, 2017
Crop development: crops have slowly been advancing with the cool weather last week. Growers have been protecting against frost after a couple cold nights last week- a bit of damage has been seen on strawberries where irrigation or row covers were not used. Day neutral strawberries are in bloom with green fruit. Early June bearing varieties are in full bloom where row covers were used; later varieties have buds in the crown. Raspberry primocanes are emerging and flower buds are beginning to show on overwintering canes. Blueberries are in bloom in southern Ontario and are quickly approaching bloom in later regions.
Blueberries: Use fungicides from different groups to control cane diseases such as phomopsis and anthracnose twig blight. During bloom, choose fungicides that control both anthracnose and botrytis. Check for scale insects on blueberry branches. We have seen more scale in the last couple years, which could be due to SWD sprays affecting natural predators of scale insects. A post-bloom application of Movento can be used when scale crawlers, the first mobile instar, are present. Use black sticky tape to determine when crawlers are active. Plan for thorough pruning next winter to prune out the old canes where the scales overwinter.
Raspberries: Growth has been slow. Primocanes are starting to emerge. It is important to protect growing primocanes and developing laterals from cane diseases with fungicide applications before and during bloom.
Strawberries: Aphids are active and populations are growing. Control is needed before or during bloom. Use Beleaf or Sivanto Prime if your fields are in bloom applying at night when bees are not active. In newly planted fields control aphids with a soil drench of Admire. Not many clipper weevils or tarnished plant bugs have been found in strawberry fields yet but scouts should be on the lookout. Control is need for plant bug if the threshold of approximately one nymph in four flower clusters is reached. Tap flower clusters into a paper plate to find tarnished plant bugs as they fall onto to the plate (Fig. 1). Check for clipper weevil at the edges of the field. If damage is found, border sprays (10-12m) should provide sufficient control.
Figure 1. Tarnished Plant Bug
Disease control during bloom: There are a number of products registered for botrytis control. Check Pub 360, page 134, for a full list of available products. Pristine, Cabrio and Switch are registered for anthracnose control. Tank mix Pristine with Captan or Maestro for botrytis protection and resistance management. Save Switch for when there is high disease pressure from botrytis and anthracnose, during warm rainy weather at bloom.