List of foliage plant diseases (Vitaceae)

This list details diseases affecting the foliage (leaves, shoots, and tendrils) of plants within the family Vitaceae, which primarily encompasses grapevines (genus Vitis). These diseases can significantly impact grapevine health, vigor, and ultimately, fruit yield and quality. Effective management strategies are crucial for sustainable viticulture.

Fungal Diseases:

• Downy Mildew: Caused by the oomycete Plasmopara viticola, downy mildew is a devastating disease characterized by oil-spot lesions on the upper leaf surface and a white, downy growth on the underside. It thrives in humid conditions.

• Powdery Mildew: Caused by various species of fungi in the order Erysiphales (primarily Erysiphe necator), powdery mildew appears as a white or grayish powdery coating on leaves, shoots, and berries. It favors moderate temperatures and humid conditions.

• Black Rot: Caused by the fungus Guignardia bidwellii, black rot affects all green parts of the vine, including leaves, shoots, and fruit. Leaf lesions are reddish-brown with a dark border.

• Phomopsis Cane and Leaf Spot (Dead Arm): Caused by the fungus Diaporthe viticola (formerly Phomopsis viticola), this disease causes small, dark lesions on leaves and shoots. It can lead to cankers on older wood, resulting in reduced vine vigor and yield.

• Anthracnose (Bird's Eye Rot): Caused by the fungus Elsinoe ampelina, anthracnose creates sunken, circular lesions on leaves, shoots, and berries. Severe infections can defoliate the vine.

• Eutypa Dieback: Caused by the fungus Eutypa lata, Eutypa dieback is a trunk disease that leads to cankers and decline of the vine. Foliar symptoms include stunted shoot growth, chlorosis, and cupping of leaves.

Viral Diseases:

• Grapevine Fanleaf Virus (GFLV): Transmitted by nematodes, GFLV causes a variety of symptoms including leaf deformation (fanleaf), shortened internodes, and reduced fruit set.

• Grapevine Leafroll-associated Viruses (GLRaVs): A complex of viruses transmitted by mealybugs and scale insects, GLRaVs cause leaf rolling, reddening of leaves (especially in red varieties), and reduced fruit quality and yield.

• Grapevine Red Blotch Disease: Caused by Grapevine Red Blotch-associated Virus (GRBaV), this disease causes red blotches on leaves, particularly in red varieties, and can affect fruit ripening.

Bacterial Diseases:

• Pierce's Disease: Caused by the bacterium Xylella fastidiosa, Pierce's disease is spread by xylem-feeding insects. Symptoms include leaf scorch, leaf drop, and eventually, vine death.

Nutrient Deficiencies:

While not diseases caused by pathogens, nutrient deficiencies can manifest as foliar symptoms resembling diseases. Common deficiencies include:

• Iron Deficiency (Chlorosis): Causes interveinal yellowing of leaves.

• Magnesium Deficiency: Causes interveinal chlorosis, particularly in older leaves.

• Potassium Deficiency: Causes leaf margin necrosis and interveinal chlorosis.

Other Factors:

It is important to note that environmental stress, herbicide injury, and insect damage can also cause foliar symptoms that may be mistaken for diseases. Accurate diagnosis is essential for effective management.