Grapes

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.

Spring frost is a significant production hazard in nearly all locations in the Mid-Atlantic however (luckily!) most areas of Maryland do not experience damage frequently compared to other areas. As with most issues in viticulture, prevention or avoidance through excellent attention to site selection is the best option to reduce risk.

Damage from low temperatures in early spring when grapevines are initiating their growth is a risk to sustainable/profitable wine grape production in the Eastern US. The majority of Maryland vineyards do not experienced a significant amount of freeze damage annually, in a major part due to proper site selection. However with the extremes of weather experienced over recent years, Maryland vineyards are at increased risk. This “TimelyVit” will give an overview of how timing and conditions of frosts/freezes during early growth can influence the level of damage.

It is critical to properly monitor and assess fruit maturity characteristics to make the appropriate management, harvesting, and winemaking decisions to produce the best quality grapes and wine possible. The first step to assessing ripeness and quality is to take a proper sample that best represents the actual ripeness stage of the cultivar in that block of the vineyard. The best way to achieve this is to collect a sample that is random, unbiased, and representative.

University of Delaware extension and Rutgers both as recently reported seeing a large increase in green stinkbugs (Acrosternum hilare or Chinavia hilaris ) in their black light traps.

Although many grape diseases do not show actual symptoms on the foliage or fruit until later in the season, it is imperative that disease management begin shortly after growth begin in the spring. Early season foliar and fruit diseases (Phomopsis, Powdery Mildew, Downy Mildew, and Black Rot) become established on the young foliage and spread to new foliage and developing cluster as growth continues.

Resources

Japanese beetles can periodically be a significant pest in Maryland vineyards. They create large holes in the younger leaves of vines and cause severe lacing and even fruit damage in heavy infestations. The population build up is typically periodic and cyclic and may require control tactics in years of large infestations. Always be extra careful with young vines as they cannot tolerate severe defoliation.

Recommended wine grape varieties for Maryland.