Grapes

Over the past few years there have been quite few cases in Maryland of injury to grapevines from herbicides that were sprayed to control weeds before planting crops on adjacent or nearby fields. Damage has ranged from some minimal leaf distortion through severe damage, crop loss, and vine death.

Grape flowers and fruit set is a very complicated process, which can be influenced by cultivar, environment, vine status and history, biotic and abiotic factors. Optimum conditions for fruit set include high light intensity, warm temperature, and adequate soil moisture and nutrients at bloom. Good fruit set is important for proper cluster formation, development, and ultimate desired maturation and harvest of fruit. The following is some basics on fruit set and some potential causes of poor fruit set.

This general term applies to the larvae (caterpillars) of a large number of butterfly/moth species (Lepidoptera) in the noctuid family that feed on buds, young shoots and leaves. Cutworm damage most commonly occurs in vineyards with weeds under the trellis or mulch, and in sandy or light colored soils.

This Timely Viticulture article is on the periodical (17-year) Brood X Cicadas. The content includes the background, life cycle, damage, and the management of the emergence of the Brood X Cicada in the vineyard.

A list of resources for Grape Pest and Weed Management

Nematodes are worm-shaped animals found in many different environments and 10% of known nematode species are parasites of plants. Plant-parasitic nematodes are thread-like, virtually invisible to the naked eye when in the soil or within plant material, and range from 1/50 to 1/8 of an inch (0.2 to 4.0 mm) long with a diameter of about 1/1000 of an inch (30 µm).

Over the past few years, harvesting of some Maryland and Eastern U.S. grapes has been complicated by the presence of Multicolored Asian Ladybeetles (MALB - Harmonia axyridis). The adult beetles can damage fruit in the field but most importantly, acts as a contaminant of the harvest, “fatally” tainting the wine made from the grapes.

Grape Flea beetles, Altica spp. (Coleoptera: Chrysomelidae), are small (4-5 mm), oval shaped, metallic blue-purple beetles that jump when disturbed.

The previous “Timely Viticulture” addressed some basic information on MALB and this message will concentrate on management tactics. Some sections of this message were intentionally repeated, but there is new information throughout.

The brown marmorated stink bug (BMSB) has become a state-wide problem in Maryland vineyards, and its range and damage is increasing. The full impact on vineyards and wine quality potential of this newly introduced pest is unclear. TimelyVit — Part 1 — was created to give growers background on the pest and this TimelyVit will address some management options. Regretfully, it must be stressed that this is a new “introduced” pest and very little is currently known of its management, thresholds for management.