Act early to beat Godronia canker


Spring application of fungicides will help prevent infection and spread.


By Judie Steeves M


ay and June are criticalmonths for detecting andmanaging Godronia canker on blueberries,


before the hotter weather of summer, advises Siva Sabaratnam, plant pathologist with the provincial agricultureministry’s Abbotsford office. Now that his work on Godronia has


been completed, he is hoping registration of some products for use against it in the fall will be approved so there will be options for growers this year. In spring, fungicides used in the


management ofmummy berry, phomopsis canker, botrytis blight and anthracnose on blueberry can prevent infection and spread of the disease early in the year, he said. The infection is spread at temperatures


B.C. MINISTRY OF AGRICULTURE ‘Flagging’ stems on highbush blueberry plants from Godronia canker.


from12 C to 22 C when there ismoisture on the plant for at least 48 to 50 hours that allows the spores to germinate and cause infection. When the hot, dry weather of summermoves in, it


generally puts a stop to the spread of godronia. Althoughmost blueberry varieties are susceptible to


Godronia, Dukes seemto be affectedmore than others. Healthy plants are less stressed and less likely to be


open to fungal diseases, so generally good cultural practices help to prevent it fromgaining a toehold. Pruning to ensure good air circulation within and


around plants helps to reducemoisture and humidity frombuilding up.When the plant canopy is less dense the foliage dries faster. Overhead irrigation should be avoided when the


canker is present, and irrigation should be scheduled for earlymorning so plants have a chance to dry quickly. All diseased branches should be pruned out and


removed at the end of the season. Godronia can be recognized in spring by the reddish-


brown lesions on one- and two-year-old stems, on leaf scars and in the axils of leaf and flower buds. Young infected buds become brown. As the season


progresses the cankers turn grey with reddish or dark- brownmargins and they expand up and down the stems to one to 10 centimetres in length. Within eight to 10 weeks theymay girdle the stem,


resulting in dying branches with reddish-brown leaves. Details of Sabaratnam’s research are also available in Punjabi on the B.C. Blueberry Council’s website.


British Columbia Berry Grower • Summer 2013 17


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