Diseases / Pests Flashcards
What is Bacterial Blight?
Bacterial… yep
Caused by the Xanthomonas ampelina bacterium, Bacterial Blight often kills young grapevine shoots. They develop dark brown streaks in early spring, and eventually wither and die. Spread by rain and compromised pruning tools, the disease can be controlled by hot water treatments and copper sprays, such as the Bordeaux Mixture.
What is Crown Gall?
Bacterial
AKA Black Knot
The Agrobacterium tumefaciens bacterium causes the Crown Gall disease in a wide variety of plant species. When affected, a vine develops tumors (galls) on its trunk, which girdle and essentially strangle the vine, withering or killing outright the portions of the vine above. The bacteria thrive in colder climates, and systemically live inside the grapevine.
What is Esca?
Fungal
AKA Black Measles, Apoplexy
One of the earliest known fungal grapevine diseases, Esca thrives in warmer climates but exists worldwide, and there is no known control or cure. Unlike other fungal diseases, Esca is the result of a complex of fungi, rather than a single organism.
What is Leafroll?
Viral
Leafroll Virus, a condition caused by a complex of at least nine different viruses, may be responsible for as much as 60% of the world’s grape production losses. Although affected vines display radiant shades of red and gold in the autumn, such beautiful colors, combined with a characteristic downward curling of the leaves, signal the virus’s malevolent side: reduced yields and delayed ripening. Leafroll Virus, spread through propagation of infected vines or by an insect vector like the mealy bug, is currently incurable but it will not kill the vine; thus, infected vines are not always removed.
What is Oidium?
Fungal
AKA Powdery Mildew
Native to North America, the Uncinula necator fungus has spread worldwide, and thrives even in humid yet dry conditions—rainfall is actually a detriment to the survival of its spores. The fungus, during its anamorph stage, is known as Oidium tuckerii. Powdery mildew affects all green parts of the plant, marking grapes, leaves, and shoots with its dusty white mildew growth.
What is Downy Mildew?
Fungal
AKA Persnospora
Another fungal disease that emigrated to Europe on North American vine cuttings, downy mildew spread rampantly through France and the rest of Europe in the early 1880s. Plasmopara viticola, the agent of downy mildew, attacks the green portions of the vine, causing leaves to drop off the vine and limiting the vine’s ability to photosynthesize.
The blue-staining Bordeaux Mixture, a spray of copper sulfate, water and lime, was developed by 1885 to prevent outbreaks of downy mildew
What is Flavescence Dorée?
Phytoplasmic
A form of grapevine yellows, Flavescence Dorée first appeared in Armagnac in 1949. Leafhopper insects and propagation of infected vines spread the disease, which will initially delay budbreak and slow shoot growth, eventually causing bunches to fall off the vine and berries to shrivel. The disease will discolor leaves, cause pustules and cracks to form, and may kill young vines. No cure exists, although insecticides may be used to control leafhopper insect populations and retard its spread.
What is Pierce’s Disease?
Bacterial
Caused by the bacterium Xylella fastidiosa and most commonly transmitted by the glassy-winged sharpshooter—a leafhopping insect found near citrus orchards and oleander plants—Pierce’s Disease is a scourge, rendering vines incapable of producing chlorophyll and killing it within one to five years.
What is Pernospora?
Fungal
AKA Downy Mildew
Another fungal disease that emigrated to Europe on North American vine cuttings, downy mildew spread rampantly through France and the rest of Europe in the early 1880s. Plasmopara viticola, the agent of downy mildew, attacks the green portions of the vine, causing leaves to drop off the vine and limiting the vine’s ability to photosynthesize.
The blue-staining Bordeaux Mixture, a spray of copper sulfate, water and lime, was developed by 1885 to prevent outbreaks of downy mildew
What is Fanleaf Degeneration?
Viral
Fanleaf Degeneration, a nepovirus spread by soil nematodes feeding on infected roots, severely curtails yields and affected vineyards must be removed. A complex of similar diseases, Fanleaf Degeneration deforms shoot growth, and leads to poor fruit set and shot (seedless) berries.
What is Black Rot?
Fungal
Native to North America, Black Rot spread to Europe with the importation of phylloxera-resistant rootstocks in the late 1800s. The disease is caused by the Guignardia bidwelli fungus, originating as a black spot on the vine’s shoots, leaves, and berries.
What is Eutypa Dieback?
Fungal
Also called dead arm, the disease is caused by the Eutypa lata fungus. Spores are carried by rain and enter the vine through pruning wounds. Common in Mediterranean climates, the disease is difficult to control as it affects a wide number of plants. Infected vines experience stunted shoot growth as the fungus releases toxins, and eventually an infected cane may die—the dead arm.
What is Bunch Rot?
Fungal
Botytis cinerea
Bunch rot is a grouping of similar diseases caused by a number of fungi species. In general, bunch rots reduce crop yields and may adversely affect the character of the wine, imbuing it with moldy off-flavors. One of the most common forms of bunch rot is Botrytis bunch rot. Known in its malevolent form as grey rot, the Botrytis cinerea fungus will break down the skin of berries and allow other yeasts and bacteria to rot the grapes. It spreads quickly throughout vineyards. However, if the fungus invades healthy white grapes under favorable conditions, it will instead result in the noble rot, a precondition for some of the world’s greatest sweet wines. Botrytis bunch rot requires warm weather and humidity of at least 90% to germinate.
What is Powdery Mildew?
Fungal
AKA Oidium
Native to North America, the Uncinula necator fungus has spread worldwide, and thrives even in humid yet dry conditions—rainfall is actually a detriment to the survival of its spores. The fungus, during its anamorph stage, is known as Oidium tuckerii. Powdery mildew affects all green parts of the plant, marking grapes, leaves, and shoots with its dusty white mildew growth.
What is Black Knot?
Bacterial
AKA Crown Gall
The Agrobacterium tumefaciens bacterium causes the Crown Gall disease in a wide variety of plant species. When affected, a vine develops tumors (galls) on its trunk, which girdle and essentially strangle the vine, withering or killing outright the portions of the vine above. The bacteria thrive in colder climates, and systemically live inside the grapevine.
