The spotted lanternfly is a pest that is deadly to grape vines. A vineyard in Pennsylvania recently reported 90% crop loss due to the spotted lanternfly. The Pierce’s Disease/Glassy-winged Sharpshooter Board has received a few spotted lanternfly updates already. Entomologists believe that the spotted lanternfly will eventually spread to California likely in the form of egg masses on rail cars or other forms of goods movement. Egg masses may be hard to detect as they often look like accumulated mud. Below are links to critical information about the spotted lanternfly.
Xyella fastidiosa is a bacterium that lives in the
water-conducting system (the xylem) of host plants and is spread from
plant to plant by sap-feeding insects that feed on xylem fluid. Symptoms
appear when significant blockage occurs within xylem vessels due to the
growth of the bacteria. (This bacterium is also responsible for alfalfa
dwarf disease and almond leaf scorch in California.) Insect vectors for
Pierce's disease belong to the sharpshooter (Cicadellidae) and
spittlebug (Cercopidae) families. The blue-green sharpshooter (Graphocephala atropunctata) is the most important vector in coastal areas.
UC Berkeley - Xylella Fastidiosa
UC IPM - Pierce's
Esca, Botryosphaeria dieback, Eutypa dieback, and Phomopsis dieback
make up a complex of "trunk diseases" caused by different
wood-infecting fungi. The foliar symptom of Esca is an interveinal "striping".
The "stripes", which start out as dark red in red cultivars and yellow
in white cultivars, dry and become necrotic. Foliar symptoms may occur
at any time during the growing season, but are most prevalent during
July and August.
of powdery mildew appear on leaves as chlorotic spots on the upper leaf
surface. Signs of the pathogen appear a short time later as white,
webby mycelium on the lower leaf surface. As spores are produced, the
infected areas take on a white, powdery or dusty appearance. On fruit and rachises the pathogen appears as white, powdery masses that may colonize the entire berry surface.
Black to brown web scarring can be seen on mature fruit, which
represents former colonies. Symptoms of powdery mildew infection include
red blotchy areas on dormant canes.
The types of plant-parasitic nematodes that become established in
a vineyard are determined by the nematodes present in the soil at
planting, the nematodes in irrigation water, sanitation and cleanliness
of nursery stock, susceptibility of the selected rootstock, the nematode
host status of cover-crops and native vegetation, and the movement of
nematodes with soil by vehicles. Of the many genera of plant parasitic
nematodes detected in soils from California vineyards, dagger, ring, and
root lesion nematodes are the most prevalent in north and central coast vineyards, and in the San Joaquin Valley.
first become apparent in vineyards 5 to 7 or more years old, but the
infections actually occur in younger vines. Perithecia, the
overwintering structures that produce spores, are embedded in a stroma
in diseased woody parts of vines. During winter rainfall, spores are released and wounds made by winter pruning provide infection sites. After a pruning wound
is infected, the pathogen establishes a permanent, localized wood
infection, which cannot be eradicated by fungicide applications.
the 10 grapevine leafroll-associated viruses (GLRaVs) are a group of viruses that cause similar symptoms in infected grapevines. They colonize and reproduce in the grapevine phloem tissue, which disrupts the flow of nutrients to shoots, leaves, and fruit pedicels. This disruption in vascular tissue stunts vines, reduces vigor, and impedes accumulation of sugars and other metabolites in the fruit. Infected vines often have fewer clusters, lower yield (up to 30-50%), and delayed fruit ripening.