Powdery mildew in roses.
This is one of the most dangerous and common infectious diseases of roses. The causative agent of powdery mildew is a fungus sferoteka pannoza (Sph. Pannosa Lev, var. Rosae Woromc h), which affects the leaves, buds, shoots and fruits of plants.
First on the affected mildew appears white roses spider or powdery coating. Then the mycelium is sealed, plaque becomes brownish-gray. Spores are formed during the summer and are carried by wind over long distances. Leaves patients with powdery mildew of roses twisted, affected areas shoots die. These roses wilt and may die during the winter.
Development of the disease contribute to excessive nitrogen fertilizer roses, calcium deficiency in the soil, lack or excess moisture, thickened landings. Rose with leathery or glossy leaves are resistant to powdery mildew.
In the fight against mildew you have to combine the right agricultural techniques (strictly follow the diet roses, avoid excess nitrogen fertilizer before budding, to feed the roses in this period phosphorus and potassium) with the use of drugs at the first sign of the disease.
To avoid infection in the garden, bought roses to dip "head" (15-20 min) in a solution of copper sulfate (1%) or in solution fundazol (0.2% - 1 tbsp. Tablespoon per 10 liters of water) and then conduct regular preventive spraying with one of the drugs:
- Infusion of mullein (1:10);
- Five-day infusion of ash (1 cup per 10 liters of water);
- Solution of potassium permanganate (2.5 g per 10 liters of water);
- Solution of soda ash and soap (40-50 g ash and 40 g soap per 10 liters of water).
Spray roses need only in sunny weather!
Located in the ash and slurry trace destroy harmful mildew mycelium. I recommend 2-3 times per season to pollinate rose ash and sprinkle it in the ground around the bushes with subsequent incorporation.
When you see roses mildew should immediately treat the affected plants (2-3 times at intervals of 4-5 days) Bordeaux mixture (1%), or a solution of copper oxychloride (0.4%), or copper-soap solution (10 liters water 20-30 g of copper sulphate and 200-300 g of soap).
To prepare the copper-soap solution: copper sulphate and soap separately dissolved in a small amount of hot water, followed by a solution of copper sulphate in a thin stream poured into the soap solution, stirring constantly; then strain the liquid. Against powdery mildew are also sulfur colloid or Karatani. Better to abandon the rose varieties that are highly affected with powdery mildew.
In very wet weather or when there is excessive watering roses sometimes affected by downy mildew: on the upper side of the leaves appear yellowish blur, Browning later, and on the underside of leaves visible plaque powdery spores. Sick leaves wither and die, shoots bend and crack, shrink; buds do not bloom. Affected downy mildew leaves to collect and burn, crop ugly shoots, and in autumn dig the soil in the rose garden.