Phomopsis Cane and Leaf Spot

We may be facing favorable conditions for the release of spores from Phomopsis viticola pycnidia which include:

• Spring showers
• Temperatures between 60-75ºF
• Free moisture for humidity near 100%

Spores are released in large quantities from pycnidia found on diseased wood at budbreak and splashed by rain onto the young growing shoots. Once growth has reached 15-18 inches the canopy forms an umbrella and helps prevent the splashing effect, therefore decreasing the need for fungicide applications.¹ The good news is that since most spores are distributed through free water, the disease is frequently confined to certain areas of the vineyard, making it relatively easy to control.² The photos below show some of the damages caused by Phomopsis. They are from UC IPM Online Grape Phomopsis Cane and Leaf Spot.³

The images below shows how Phomopsis appears on dormant canes:

Knowledge of the lifecycle of phomopsis is important in aiding in the management and treatment of the disease.¹

Much more informationcan be found in the references listed below.
References:
1. J.W. Pscheidt and R. C. Pearson, Phomopsis Cane and Leaf Spot, Cornell Cooperative Extension, NYS Agricultural Experiment Station, Disease Identification Sheet No. 6 (Revision), 1991.
2. Stephen J. Vasquez, Protecting grapevines from Phomopsis Cane and Leaf Spot, April 2, 2009, San Joaquin Valley Viticulture, California Viticulture Information.
3. William Nail, Grapevine Cultivation in Connecticut, The Connecticut Agricultural Experiment Station, New Haven, Bulletin 1007, May 2007.
4. UC IPM Online Grape Phomopsis Cane and Leaf Spot.