Grapes are one the crops that benefit from the AmeriBest Mist Sprayer application for fungicides, insecticides and foliar feeding because the AmeriBest Mist Sprayer will deposit spray droplets on the underside of the leaves. 1-2 gallons per acre will effectively cover your crop with swath widths of 40' to 75'. This is next to impossible with conventional boom or aerial spraying methods.
AmeriBest Mist Sprayers provide better coverage at a much lower cost than you would incur with other application methods. Many producers/growers have sprayed their grapes with an AmeriBest Mist Sprayer. They have reported excellent results at treatment levels 25-30% below conventional spraying methods and in half the time!
is one of the most serious diseases of grapes in the United States. Crop losses can range from 5 to 80 percent, depending on the amount of disease in the vineyard, the weather, and plant susceptibility. The fungus, Guignardia bidwelli, can infect all green parts of the vine. Most damaging is the effect on fruit. Later fruit infections can destroy many grapes, even the entire crop.
The fungus overwinters in mummified berries on the soil or in old berry clusters that hang in the vines. Spores of the fungus are produced within the diseased fruit and infect leaves, blossoms and young fruit during spring rains. Fruit infections occur from midbloom until the berries begins to color.
, or gray mold, is a disease that exists in all vineyards worldwide. The disease is caused by the fungus Botrytis cinerea and is associated commonly with the decay of ripe or nearly ripe grapes. Temperature and damp climates favor disease development. The bunch rot phase of the disease causes the greatest economic losses.
Botrytis bunch rot also infects numerous wild hosts and cultivated plants. The fungus can live on these alternate hosts dead tissue. The pathogen overwinters on bark and in dormant buds. In the spring, spores are produced by the fungus and infect leaves and young grape clusters. Fungicide sprays are suggested on very susceptible varieties during the bloom period. The sprays will reduce the number of infected flower parts and the incidence of young fruit infection. Any practice that reduces skin cracking or skin punctures near harvest helps control ripe fruit rot. Preharvest fungicide applications are also recommended.
occurs wherever it is warm and wet during the growing season. The disease is caused by the fungus Plasmopara viticola, which overwinters as spores in fallen leaves. Downy mildew infection can become a severe problem when a wet winter is followed by a wet spring and a warm summer with a lot of rainfall. The pathogen attacks all green parts of the vine, especially the leaves. Lesions on leaves are angular, yellowish, sometimes oily, and located between the veins. As the disease progresses, a white cottony growth can be observed on the lower leaf surface. Severely infected leaves will drop. Young berries are highly susceptible, appearing grayish when infected. Berries become less susceptible when mature. Infected berries remain firm compared to healthy berries, which soften as they ripen. Eventually, infected berries will drop.
Fungicides are the most important control measure for downy mildew. They should be applied just before bloom, 7 to 10 days later (usually at the end of bloom), 10 to 14 days after that, and finally, 3 weeks after the third application. For cultivars very susceptible to downy mildew, or where the disease was severe the previous season, an additional application is suggested about 2 weeks before the first blossoms open.
is one of two distinct diseases that used to be referred to as dead arm, and is widely distributed in vineyards. The disease can weaken vines, reduce yields, and lower fruit quality. This disease is often the first disease of the growing season to appear in the vineyard. Infections on new shoots first appear as reddish spots about 1/16-inch in diameter. Infected portions of the leaf turn yellow then brown. This fungus also causes a fruit rot. Infected fruit will turn brown, shrivel, and eventually drop. In winter, cane infections can be observed.
The disease is caused by the fungus Phomopsis viticola. The fungus overwinters in bark and leaf petioles. In the spring, especially under wet conditions, spores produced by the fungus exude from infected tissue and are splashed onto shoot tips. Only very young tissues are infected. In summer, the fungus becomes inactive, but by fall it resumes activity. Infection in the vineyard is localized because disease is spread mostly within the vine rather than from vine to vine. If the disease is not controlled, with each increasing year it will become more severe in the vineyard.
Phomopsis cane and leaf spot can be controlled by a combination of sanitation and fungicide application. The cane and leaf infections can be prevented by one or two early-season fungicide sprays. Fruit and cluster stem infections occur from bloom until the fruit are pea sized. Regular fungicide applications are necessary to prevent disease.
is an important fungal disease of grapes. If not controlled on susceptible cultivars, the disease can reduce vine growth, yield, quality, and winter hardiness. The fungus can infect all green tissues of the grapevine. It was previously thought that the fungus overwintered inside dormant buds of the grapevine. Research has shown that almost all overwintering inoculum comes from cleistothecia, which are fungal fruiting bodies that overwinter primarily in bark crevices on the grapevine. In the spring, airborne spores (ascospores) released from the cleistothecia are the primary inoculum for powdery mildew infections.
Ascospores are carried by wind. They germinate on any green surface on the developing vine, and enter the plant resulting in primary infections. The fungus grows and another type of spore (conidia) is formed over the infected area after 6 to 8 days. The conidia and fungus mycelia give a powdery or dusty appearance to infected plant parts. The conidia serve as "secondary inoculum" for new infections throughout the remainder of the growing season. It is important to note that a primary infection caused by one ascospore will result in the production of hundreds of thousands of conidia, each of which is capable of causing secondary infections. Therefore, as with black rot, it must be emphasized that early season control of primary infections caused by ascospores is necessary. If primary infections are controlled until all the ascospores have been discharged, the amount of inoculum available for causing late season (secondary) infections is greatly reduced.
Insects in Grapes
are known to feed on grapes. The larvae hide in the soil litter below the grape trellis and climb onto vines on warm nights to feed on developing primary grape buds. Only during bud swell are cutworms able to inflict serious damage to a vineyard. To examine for cutworms, search under the bark and in the soil litter beneath a vine with damaged buds, or search the vine with a flashlight after dark.
are spider mites that are especially severe in vineyards adjacent to apple orchards. Both adults and nymphs pierce the cells on the leaf undersides and extract plant juices. Heavily infested leaves take on a characteristic bronze coloration.
are very serious insect pests affecting grapes. Two and occasionally three generations of moths hatch per season.