Grapes | University of Maryland Extension

Updated: August 19, 2022

Crop Development Sampling

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.

Timely Viticulture Timeline: Pre-Harvest

Updated: July 7, 2022

Grape Root Borer-Background, Scouting, and Management

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.

Timely Viticulture Timeline: Mid Season, Pre-Harvest, and Harvest

Updated: June 14, 2022

Be on the Lookout for Green Stink Bug

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.

Fig. 1.) Adult Green stink bug. Photo by David Cappaert, Bugwood.org

Updated: May 11, 2022

Early-Season Disease Management

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.

Updated: May 11, 2022

Guidelines for Developing an Effective Fungicide Spray Program for Wine Grapes in Maryland (FS-848)

The purpose of this fact sheet is to help wine grape growers in Maryland develop effective fungicide spray programs to manage a complex of five major fungal diseases affecting vines and fruit: powdery mildew, downy mildew, black rot, Botrytis bunch rot, and Phomopsis cane and leaf spot. The spray schedules below suggest several options for each spray but do not include all fungicides registered in Maryland for control of these diseases. Three supplemental tables are provided to further assist growers in choosing fungicides. Table 1 rates the effectiveness of all fungicides mentioned in the fact sheet against these diseases. Information on effectiveness is intended as general guidance only. Results in a given vineyard will depend on the weather, disease pressure (level of inoculum present), canopy management, age of vines, fungicide formulation and rate, and spray intervals and coverage. Table 2 lists resistance-prone fungicides by chemical class (mode of action) to help growers choose rotational partners with different modes of action fungicides mentioned in this guide. Author: Anne DeMarsay, Ph.D., The Fruit DoctorTM; Title: The New Guidelines for Developing an Effective Fungicide Spray Program for Wine Grapes in Maryland, 2012 (FS-848)

Updated: May 7, 2022