Scouting updates
Disease scouting takes place at the West Madison ARS vineyards every week. Scouting begins in late dormancy to early bud swell and is completed several weeks after harvest. Check back weekly for updates! Several cold climate grape varieties are observed including Marquette, Frontenac, La Crescent, Brianna, Petite Pearl, Itasca and several table grape varieties. Not all symptoms are observed on all varieties; please see tables below with disease susceptibility data collected by Dave Jones and Dr. Patricia McManus during 2015 and 2016 growing seasons.
We thank Courtney Cameron and Emma Nelson for scouting and providing photos.
To find updates on cold climate grape phenology and insect pest scouting throughout the growing season, visit https://fruit.wisc.edu/
Disease Susceptibility Tables
2022 Season - Grape Disease Scouting Updates
May 23, 2022
With shoots in the 4-8 inch range, oil spots (early downy mildew symptom), black rot, and Phomopsis are becoming prevalent.
May 16 & 19, 2022
Rain this week provided favorable conditions for anthracnose activity. Additionally, the 90-degree temperatures this week quickly pushed the grapes from bud swell to 1-3 inch shoots.
Anthracnose lesions with translucent centers and dark brown margins visible on grape leaves.
May 10, 2022
Phomopsis fruiting bodies and anthracnose lesions are visible on canes. Vines are at early-late bud swell.
2021 Season - Grape Disease Scouting Updates
2021 season comments
In late April, frost events occurred across the state of Wisconsin and freeze damage occurred on vines in several counties. Drought conditions persisted in May and June with several consecutive days at or above 90°F; vines were irrigated. Early season disease pressure was low. By late June there was an increase in humidity with several rain events; temperatures dropped to the 70s. July temperatures rose again to 80-90°F with high humidity. Conducive conditions increased disease pressure for powdery mildew especially in highly susceptible varieties. August was moderately warm (70-80°F) with a few rain events.
August 26, 2021
Anthracnose lesions observed on several shoots and leaves.
July – September 2021
Powdery mildew is severe on highly susceptible varieties. Chasmothecia (overwintering fungal fruiting bodies) are beginning to form on leaves.
Powdery mildew on Brianna berries (left) and leaves (right)
July 6, 2021
Powdery mildew has infections observed on several varieties.
Severe powdery mildew infection on Brianna berries. *Brianna is highly susceptible to powdery mildew infections on leaves, fruits and the rachis.
June 28, 2021
Powdery mildew is showing up on Brianna and La Crescent berries and leaves. Phomopsis lesions are visible on Marquette leaves and vines. Several varieties have black rot infections and fruiting bodies are visible on Petite Pearl leaves.
Black rot foliar lesions (left); Powdery mildew on Brianna berries (right).
June 9, 2021
Black rot lesions observed on susceptible varieties, some lesions displayed signs of fungal spore production. Phomopsis leaf spot observed.
Black rot lesion with fruiting bodies on Petite Pearl leaf (left); Phomopsis leaf spot (middle); Early powdery mildew symptoms (right).
May 20, 2021
Some leaves are developing chlorotic spots; early symptoms of powdery mildew infection.
May 12, 2021
By now, vines with cold damage are obvious and display no bud development. No foliar disease symptoms observed.
May 6, 2021
1-3 inch shoots are forming on most varieties. Anthracnose lesions and Phomopsis fruiting bodies are visible on the canes.
April 22, 2021
Phomopsis fruiting bodies and anthracnose lesions are visible on canes.
Phomopsis fruiting bodies (left) and old anthracnose lesions (right).