Symptoms of pistachio leaf spot disease appear in the form of dry brown spots on both sides of the leaf, followed by paleness or redness of the leaf blades. The spots gradually extend toward the center, so the leaves wither and fall early. In this article on your website, World of Plants, we will review the causes and symptoms of pistachio leaf spot disease and how to combat it effectively to preserve the pistachio plant.
Symptoms of pistachio leaf spot disease
The disease causes circular to irregular, brown to dark brown, necrotic spots on both sides of the leaf. These spots may increase in abundance on the leaves, reaching a diameter of between 1 and 2 mm. Over time, the leaf gradually turns pale green and then brown, starting at the tips and extending toward the center.
Severe infections may lead to leaves drying out and falling prematurely. Very small spots can also appear on the fruits. If the disease spreads epidemically, this can lead to premature defoliation and reduced tree activity. Attacks usually begin in April from pollen found on leaf litter left over from the previous year.
Causes of pistachio leaf spot disease
Symptoms are caused by infection with several fungi of the genus Mycosvarella, especially Mycosvarla pestacina in the Mediterranean region. The fungus hibernates on fallen leaves and debris left in the infected soil from previous seasons. The primary contamination occurs through the fungal pollen found on these leaves, where rain spray helps disperse the spores.
Secondary infections are caused by other types of germs that are also spread through rain or sprinkler water, even late in the season. High temperatures between 20 and 24 degrees Celsius and a humid and foggy climate are considered favorable conditions for the spread and reproduction of this pathogen.
Organic control of pistachio leaf spot disease
When the first symptoms appear, spray with copper or products containing sulfur, and spray after the fruit reaches about 1 cm in size to avoid toxic damage to very small fruits.
Collect fallen leaves and burn them.
When the first symptoms appear, spray with copper or products containing sulfur, and spray after the fruit reaches about 1 cm in size to avoid toxic damage to very small fruits.
It is important to diversify the use of different active ingredients to avoid the development of fungal resistance. Preventive treatments from the bud growth stage are also effective in preventing the onset of the disease.
Preventive measures for pistachio leaf spot disease
- Inspect the orchard regularly to detect the initial appearance of spots.
- Collect fallen leaves and burn them.
- Fertilize trees or enrich the soil with organic matter to improve the natural resistance of plants.
- Plan to prune trees annually during dormancy to improve ventilation and reduce the risk of infection.
- Clear the garden and the areas around the plants of replacement weeds.
- Avoid touching diseased plants in wet weather to prevent the spread of the pathogen.
- Use drip irrigation systems instead of sprinkler irrigation.
- Bury dead leaves by deep tilling in late fall and early winter.
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References
Pistachio leaf spot - plantix
Pistachio tree diseases: causes and treatment - kayftazra3
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