Tobacco Powdery Mildew (Erysiphe cichoracearum)
The disease occurs only in the field period. It usually occurs in the bottom-bottom leaves of tobacco that has taken its normal size. Symptoms are always on the upper surface of the leaves. It initially appears as round white spots 3-5 mm in diameter, then enlarges to cover the entire leaf surface. The upper surface of the leaf looks like it has been sprinkled with ash. In conditions suitable for the disease, symptoms also appear on the petiole, stem and flower capsule.
The disease can cause economic damage from time to time. It is known by names such as "San" "White Mold" among the producers. Since the part of the tobacco plant used as a product is the leaves, the loss of product in a leaf damaged by powdery mildew is equal to the area covered by the disease. Since it changes the chemical structure of the diseased leaves to a large extent, it destroys its quality.
In our country, powdery mildew disease occurs under suitable environmental conditions wherever tobacco is grown.
The pathogen has a very wide host range. The most important ones in this host series are cucumber, pumpkin, melon, watermelon, okra and sunflower. The pathogen can also cause disease in some weeds.
—Tobacco should not be planted in shady places and on water-holding land.
—Planting should be done with normal spacing and distance and frequent planting should be avoided.
—It should not be too late to break the last hands.
—Tobacco should not be grown near places where vegetables such as okra, cucumber, zucchini and melon are grown. If this is not possible, control methods against vegetable powdery mildew must be applied to prevent contamination.
—Weeds in the field should be cleaned.
—The bottom leaves should be stripped early.
—Leaves with powdery mildew should be plucked and buried.
Spraying is started as soon as the first powdery mildew spots are seen. One application may be enough. If the epidemic continues, spraying is continued, taking into account the duration of the drug used.
Spraying should be done in such a way as to form a thin film layer on the lower and upper surfaces of the leaf. (Tobacco Powdery Remedies)