IPM practices to be implemented:
- Vineyard Mapping, see discussion below.
- Pruning to Reduce Overwintering Disease Inoculum, see discussion below.
- Grape Berry Moth Risk Assessment Protocol, see discussion below.
- Weed Management, see discussion below.
Vineyard blocks should be mapped for two reasons. The first is to obtain the true dimensions of fields so that acreage can be accurately calculated. In this way, correct rates of a material can be applied, and waste is avoided. The second reason for mapping is to pinpoint the locations of pest infestations. The map can then be used to develop a pest history of the field, making future management decisions easier.
A vineyard map should include not only the vineyard but the surrounding terrain as well. Knowing whether wooded edges are present or absent is critical in assigning a risk category for the Grape Berry Moth Risk Assessment protocol. Wooded edges also extend wetting periods in a vineyard block. Anything that will hamper airflow through a vineyard should also be displayed on the map. Figure 1 provides an example of a good field map. The numbers designate different fields.
Figure 1. Vineyard map
Removal of infected canes, cordons, trunks, or fruit during dormant pruning can be especially important in the management of Phomopsis Cane and Leaf Spot, Eutypa dieback, and black rot. An understanding of how these pests overwinter leads to the removal of infected tissues, which significantly reduces the primary inoculum available for the upcoming season. This significantly reduces disease pressure and thus, the amount of fungicide needed for management. For more information on a particular disease or photographs of its signs and symptoms, please consult the grape IPM disease identification sheets.
Phomopsis Cane and Leaf Spot 277k pdf file
Black fruiting bodies (pycnidia) that overwinter in infected canes and rachises characterize this disease. Numerous lesions will give cane surfaces a blackened, scabby appearance. Phomopsis Cane and Leaf Spot is most likely to become a problem when the Phomopsis fungus is allowed to build up on dead canes in the vines. Because inoculum remains viable in the wood for several years, hedged vineyards are particularly at risk of incurring economic losses from Phomopsis. If Phomopsis is a problem in vineyards that are either hedged or minimally pruned, hand follow-up is suggested for the removal of severely infected canes.
Rot 548k pdf file
The black rot fungus overwinters in mummified fruit on the vine and the vineyard floor. The fungus also overwinters in large, black, elliptical lesions on infected shoots. Cane lesions may contribute to breakage by wind if not removed prior to the growing season. Inoculum from both the mummified fruit and the shoot lesions is used up during the following growing season. Inoculum from mummified fruit on the vineyard floor generally is depleted shortly after bloom. However, mummies overwintered in the canopy may produce primary inoculum into September. Removal of mummified clusters from the canopy during pruning and spring cultivation to bury mummies on the vineyard floor, in areas where erosion is not a concern, can contribute to a significant reduction in inoculum.
Dieback 311k pdf file
In the winter, during rainfall or snow melt, Eutypa ascospores are released from fruiting structures on dead, infected wood. Dispersed by the wind, the ascospores cause infection when they enter fresh pruning wounds. Infected arms or trunks, if not removed the previous season, should be removed in late spring to reduce the chance of reinfection. Because Eutypa moves slowly through vines, reinfection can be reduced by double cutting. After late-spring removal of diseased wood, complete removal of the trunk or cordon in midsummer can reduce the number of reinfection sites. Any infected wood or stumps should be removed from the vineyard and burned.
Gall 294k pdf file
Characteristic symptoms of this bacterial disease are fleshy galls, produced in response to infection in a vineyard or nursery. Galls are mostly found on lower trunks near the soil line but also may form at budding or grafting sites. Gall expression is determined by the extent of predisposing wounds, the grape cultivar, and the strain of the pathogen. Galls in the dormant season will be corky and dry. Inoculum survives in vineyards within galls and systemically infected vines. The strain of crown gall pathogen that infects grape may survive in decaying grape roots and canes in soil for at least two years.
Freeze injury and injury from budding and grafting are important predisposing factors for crown gall development. Therefore, management practices that reduce injury are useful in managing the disease. Hilling above the union of grafted vines protects buds from freezing and ensures their survival should new scion shoots be needed to replace galled trunks. The use of multiple trunk vines and yearly replacement of dead trunks with renewals helps to manage the disease to an economic level.
The dormant season is the time to rate a vineyard's risk for grape berry moth as high, low, or intermediate. Refer to New York's Food and Life Sciences Bulletin 138, Risk Assessment of Grape Berry Moth and Guidelines for Management of the Eastern Grape Leafhopper (appendix 2) (717k pdf file) for information on assigning vineyard risk categories.
The science of managing vineyard weeds between and under rows is undergoing many changes as this manual goes to press. Concern over groundwater contamination and surface runoff into rivers and lakes has led researchers to develop weed management programs that decrease the reliance on chemicals that persist in the soil. Research in postemergence weed management programs is currently underway using Roundup and Gramoxone. Research projects have also tested other postemergence herbicides, which are currently awaiting registration at the state level. Consult the following issues of Grape Facts and the Penn State University Weed Identification Sheets (appendix 3), and the current edition of New York and Pennsylvania Pest Management Guidelines for Commercial Grape Production, for assistance in designing a vineyard weed management strategy.
Grape Facts: Managing Weeds in New York Vineyards