Crop Diagnostic Lab Report

Week of June 29 - July 3, 2009

Wheat streak mosaic virus has been diagnosed in two wheat samples this week (Pembina, Southwest).  Two samples of wheat with leaf tip injury from environmental conditions such as wind and high temperature were received (Southwest).  Two samples of wheat with leaf yellowing caused by an undetermined stress were received (North Parkland).  One sample of wheat with symptoms of chemical injury from glyphosate was received (Red River).  One sample of oats with leaf tip injury from environmental factors as well as Pyrenophora leaf spot was received (Southwest) and one with just leaf tip burn from environment (Pembina).  One sample of barley with symptoms of group 1 chemical was received (Pembina).

Wheat – wind and or high temperature can result in injury of leaf tips of small grains. 

One sample of sunflower with rust and hail damage was received (Southwest).  Four samples of canola with symptoms of group 2 injury were received (Southwest, Pembina, North Parkland).  Group 2 chemicals can cause stunting and growth from the leaf axils.  One sample of canola with stem bends related to wind lodging was received (South Parkland).

Canola – group 2 injury can cause stunting and development of growth from leaf axils.

Two samples of field peas with symptoms of chemical injury were received (Pembina, South Parkland).

One sample of alfalfa with chemical injury was received (Southwest).  One sample of red clover with symptoms of poor growth was received and found to be affected by Fusarium root rot (Red River).

For spruce, one sample was received with a severe infestation of spruce bud scale (Eastman).  These insects can go unobserved until the infestation is severe since they look similar to the tree buds and tend to cluster around twigs and nodes.  A black mould will grow on the insect excretions.  Twigs may die back with severe infestations of the insect.  One sample of spruce was diagnosed with injury from an undetermined insect that has punctured the new needles and shoots resulting in withering of the new shoot and needle growth (North Parkland).

Spruce – spruce bud scale insects can cluster on the stem and their secretions favour the growth of a black superficial mould growth called sooty mould.

One sample of Evan’s cherry showing rotting of the fruit on the tree was diagnosed with the disease known as brown rot (Red River).  One sample of chokecherry was received that showed the leaf disease known as shot hole due to the tendency of the infected spots to drop out of the leaf leaving holes (North Parkland).  Two samples of apple with fireblight were received (Red River).

Cherry – brown rot is a common fruit disease that causes a rot of the fruit but can also kill shoots and twigs.

 

The Diagnostic Lab Report is prepared by Mardi Desjardins, Crop Diagnostic Centre, Manitoba Agriculture, Food and Rural Initiatives, 201-545 University Crescent, Winnipeg, Manitoba R3T 5S6. Phone: 204-945-7707 Fax: 204-945-4327.