Grapes

The grape root borer (GRB), Vitacea polistiformis (Harris), is an insect pest native to the Eastern United States. Its range is from the central Midwest (west) to the Atlantic Ocean (east) and from Florida and Texas (south) to Vermont and Michigan (north). GRB is a pest of all commercial grape types and feeds on native Vitis. It has a long life cycle and takes many years for it to do significant damage to grapevines. However, once grape root borers are present in a vineyard, the unlimited susceptible food source can dramatically increase the infestation. The grape root borer effect may not be immediately apparent on the vines, but once the number of larvae reaches a sufficient level, damage can be significant. Because it is an ("invisible") root tunneling pest, many growers are unaware of the economic damage being caused by GRB.

At 3 to 4 weeks after bloom, the risks of black rot (BR), Phomopsis (Ph; including cane and leaf spot, and fruit rot), and powdery mildew (PM) are decreasing. Downy mildew (DM) will be the main threat. While most Botrytis bunch rot infections occur around bloom and fruit set, bunch closing and veraison may also be critical points for protection when weather conditions are favorable for infection, especially on susceptible varieties.

Downy mildew is now a year-long challenge for grape growers in the East. Downy mildew is often difficult to manage because it requires specific weather conditions to become a serious threat, but it can develop into an epidemic very quickly in favorable weather.

Botrytis is a major disease threat as harvest approaches. Botrytis cinerea is a fungus that affects many plant species, especially wine grapes, where it is commonly known as Botrytis bunch rot or gray mold.

Pierce’s Disease—Background and Management for commercial grapes.

Herbaceous aroma in wines, such as “bell pepper” or “stemmyness,” is caused by a family of chemicals known as methoxypyrazines (MPs).

Pre-planting renovation and soil conditioning information for new vineyards and small fruit agriculture such as grapes, strawberries, and blueberries.

Multi-small fruit spray program for the control of major small fruit pests and diseases.

The Spotted Lanternfly (SLF) is now confirmed in Cecil and Harford Counties in Maryland, and populations in Pennsylvania, New Jersey, Delaware and Virginia have been growing. The pest has been impacting vineyards in Pennsylvania. What is clear at this junction is that (1) grapevines are a favorite host of this pest and, (2) its feeding damage coupled with winter cold stress can cause vine death. At ground zero in Pennsylvania, feeding from this pest, combined with the moderately cold winters of 2017/18 and 2018/19 has done significant damage to multiple commercial vineyards.

Some early cultivars in many vineyards are just starting to bloom. This is a critical time for taking tissue/petiole samples to assess the nutritional status of your vines. Remember all vineyards with income of >$2500 per year MUST have an approved nutrient management plan and MDA conducts regular monitoring to be sure you are in compliance. Recent analyzed tissue samples are at the core of the plan. The following are some timely considerations.