Apple Update: May 11, 2016

Crop Stages

Apple buds are at king bloom to full bloom in Essex County; full pink to king bloom Niagara Region, Chatham-Kent, Lambton, Middlesex, Elgin and Norfolk Counties; first pink to full pink in the GTA and Simcoe County; ½” green to tight cluster in Durham Region, Northumberland County and the Ottawa Valley.

Production

Pruning is still occurring in some orchards. Tree planting is still well underway. Frost occurred in a few spots in Central and Eastern Ontario, apple buds were not as developed in these areas affected and therefore should have been hardy enough to have withstood it. Eastern Ontario has been experiencing a dry spring. Bee hives are being placed into orchards that are at full pink to first bloom.

Diseases

Risk of fire blight still remains relatively low in most regions. However, based on the Ontario prediction maps, areas in Essex may see high to extreme risk of infection later this week if fire blight is active in the neighbourhood. Bacterial ooze has been observed on fire blight cankers.

Orchards that had an extended rain early last week experienced another scab infection period. Lesions may develop over the next week or two if exposed tissue was not covered during infection periods at the end of April. Many areas in the southwest have accumulated enough degree days to now be in a period of rapid ascospore maturity. It will be critical to apply a protectant fungicide prior to the next wetting event as the risk of infection will be high.

Many growers are switching from sulphur to systemic fungicides for powdery mildew in orchards that have reached pink. An aggressive powdery mildew program will be needed during periods of rapid growth in orchards that had issues last year.

Cankers caused by various pathogens, including black rot and Cytospora spp. are being reported in numerous orchards. This is likely a result of winter injury that occurred during the extreme cold periods of 2013/2014 and 2014/2015. For more information on some of the more common types of cankers, see Alert: Cankers in Apple Orchards.

Insects

Low numbers of oriental fruit moth continue to be caught in early areas. No biofix has been set yet. Codling moth and San Jose scale traps are going up in orchards that have reached pink growth stage.

Apple leafcurling midge adult flight  has spiked this week in monitoring sites in Norfolk County (see photo). Eggs have been found on new terminal shoots. Larvae will hatch in approximately 2-10 days after eggs have been laid, depending on temperature.

Small spring-feeding caterpillars are present on new terminal shoots, feeding on developing leaves and buds.

Mite eggs can be found in large numbers in some orchards. Some adult activity has been observed. Later regions may still have a small window of opportunity to apply oil, though the risk of frost in recent days has made this difficult.