Grape IPM in the Northeast
Third Week in July
IPM practices to be implemented
- Grape Berry Moth Risk Assessment protocol: damage threshold is 6 percent damaged clusters, see discussion below.
- Grape Leafhopper scouting, see discussion below.
- continue disease management protocols, if applicable
Scouting for grape berry moth damage should be accomplished for low- and intermediate-risk vineyards at this time. The sampling procedure for Grape Berry Moth Risk Assessment is to select four sites in each vineyard to be sampled: two on the vineyard edge - a wooded edge if there is one (areas 1 and 2, fig. 2 below) and two in the center of the vineyard (areas 3 and 4, fig. 2 below). Visually inspect, at random, 10 clusters on each of 5 vines (a total of 50) in each of the four areas. One damaged berry counts as a damaged cluster. At each site 50 clusters are examined, for a total of 200 clusters per vineyard.
Figure 2. Sampling sites for Grape Berry Moth Risk Assessment
The damage threshold at this scouting is an average of 6 percent damaged clusters. Both the interior and the edge of the vineyard should be scouted.
Example of Grape Berry Moth Sampling
Early-season sampling - counting damaged clusters (third week in July):
- 7 damaged clusters (at least one berry/cluster exhibits grape berry
moth damage) are found in area 1, and 4 damaged clusters in area 2:
7 + 4 = 11 percent damaged clusters on the vineyard edge (11 out of the 100 examined in areas 1 and 2)
- 2 damaged clusters are found in area 3, and 1 damaged cluster in area
2 + 1 = 3 percent damaged clusters in the vineyard center (3 out of the 100 examined in areas 3 and 4)
If the scouting reveals damage exceeding the 6 percent damage threshold, the area needs to be treated with an insecticide in early August. In the example above, the grower may wish to treat only the edge of the vineyard, as the vineyard interior is below threshold.
For complete information on grape berry moth scouting, consult 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) (907k pdf file).
Vineyard blocks in low- and intermediate-risk categories should be scouted for eastern grape leafhopper injury in conjunction with grape berry moth scouting. There is no need to scout for leafhopper injury in high-risk blocks because sprays applied for grape berry moth in early August will also control leafhoppers. Two procedures - nymph counting and leaf damage evaluation - are available to assess the need for an insecticide application. A treatment threshold of five leafhopper nymphs per leaf is used in the nymph-counting procedure, described in 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).
A simpler, faster procedure than counting nymphs involves the use of visible leaf stippling (leafhopper injury) as a guide to the severity of the leafhopper infestation. In this procedure, a sample of leaves is examined and compared to a photograph showing moderate leaf injury symptoms (fig. 3 below). If the leaf has more stippling than that shown on the photograph, classify the leaf as "damaged." At each of the four grape berry moth sampling sites, randomly select one shoot from each of five vines. On each shoot examine five leaves, starting with the third leaf from the base of the shoot (generally the first fully expanded leaf). A total of 50 leaves (5 vines X 5 leaves X 2 sites) at the vineyard edge and 50 leaves in the vineyard interior should be examined.
If more than 10 leaves in the entire sample (10 percent of the leaves examined) are classified as "damaged," an insecticide treatment is warranted to prevent economic injury. Both the edge and the interior of the vineyard block must be scouted. As with grape berry moth, leafhopper infestations may be concentrated at vineyard edges, and only a portion of the vineyard may require treatment.
Figure 3. Leafhopper damage. To use leafhopper injury as a treatment guide, compare each leaf sampled with this photograph. If the leaf has more injury than that shown in this photo, classify the leaf as "damaged."