St Pepin Grape Problem - Ask Extension
Hello, I have a problem with my St. Pepin Grapes. The Clusters are poorly developed and have a poor fruit set. I have sent some pictures for reference...
Knowledgebase
St Pepin Grape Problem #658108
Asked June 30, 2020, 1:02 PM EDT
Hello, I have a problem with my St. Pepin Grapes. The Clusters are poorly developed and have a poor fruit set. I have sent some pictures for reference. Is this a nutrient deficiency? Or could it be from the late snow and frost that we had in the late spring? Is there something I didn't do, or need to do? Any advice will be greatly appreciated. Thank you, Mark.
Lenawee County Michigan
Expert Response
Dear Mark,
based on the color of the leaves, I don't think this reduced fruit set is dictated by any nutrient of water limitation in your vineyard. I think is the consequences of weather conditions. Do you recall the weather at the time of bloom? Grapevines are really sensitive at bloom to poor climatic conditions (rain and low temperature). In fact, overcast, wet, cool can result in very ‘poor’ fruit set and loose clusters. An extended period of low (<15°C/59°F) temperature interferes with the development of pollen and pistil during the flowering process and the correct development of the ovule after fertilization. Rain during the flowering period inhibit pollination and fertilization and reduce the germination of pollen grains.
based on the color of the leaves, I don't think this reduced fruit set is dictated by any nutrient of water limitation in your vineyard. I think is the consequences of weather conditions. Do you recall the weather at the time of bloom? Grapevines are really sensitive at bloom to poor climatic conditions (rain and low temperature). In fact, overcast, wet, cool can result in very ‘poor’ fruit set and loose clusters. An extended period of low (<15°C/59°F) temperature interferes with the development of pollen and pistil during the flowering process and the correct development of the ovule after fertilization. Rain during the flowering period inhibit pollination and fertilization and reduce the germination of pollen grains.
