Grapevine trunk diseases (GTD) are the most destructive disease complexes in grapes, causing significant economic losses due to reduced yields, increased management costs and shortened vineyard lifespan. University of California Cooperative Extension Plant Pathologist Dr. Akif Eskalen estimates more than 80% of grapevines in California are impacted by GTD. While symptoms are not always visible, current management practices are labor intensive and costly.
1. PRUNING OR HARVEST INJURY
More than 95% of trunk disease infections are associated with pruning or other cultural practices, such as mechanical harvesting.
2. OPEN WOUNDS, OPEN FOR INFECTION
These practices can leave wounds exposed and open to infection by pathogens. The spread of the pathogens usually happens during rain events.
3. PATHOGENS GROW IN THE VINE
These fungal pathogens grow and decay the xylem and phloem, slowly killing vines.
4. DEAD VINES PRODUCE SPORES
Spore-producing bodies grow in dead vine wood.
5. SPORES SPREAD TO NEW VINES
In the presence of water, spores are released and dispersed by wind to infect fresh pruning wounds.
Over time, this leads to huge losses for grape growers.
Timeline of Destruction
Disease Development by GTD Pathogen
Rhyme fungicide via drip reduced disease development as measured by lesion length compared to the untreated check. Lesion length was reduced by 13%-53% depending upon the pathogen.
*Dr. Akif Eskalen, University of California Davis Extension Research.
**This timeline represents the estimated yield reduction caused by GTD. Estimates are based on industry research and assumes a peak yield of 6 tons/A.
This Rhyme fungicide recommendation is made as permitted under FIFRA Section 2(ee) for the management of wood disease complex on grapes in California. This recommendation has not been submitted to or approved by the EPA. The 2(ee) expiration date is 12/05/2024.
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