Katie_89
Full Member
Posts: 12
Joined: Tue Apr 25, 2017 11:26 pm

Powdery Mildrew

Hi all!!

So have a small drift rose with powdery mildew. Bought a spray last week and hsve treated it twice with sadly no luck. What is the next best step??
Its still budding and green. The mildew is mainly on new buds

imafan26
Mod
Posts: 13961
Joined: Tue Jan 01, 2013 8:32 am
Location: Hawaii, zone 12a 587 ft elev.

if there are no edibles around, then use Bayer Rose and Flower care. It does contain a systemic to control fungal diseases like powdery mildew and black spot. Make sure the roses are spaced properly and get good air circulation. Prune and feed them after each bloom cycle. It does help to get roses that are more disease resistant to start with. Because I live in a humid environment, I purposely select for roses with glossy leaves. I also like the big tea and English roses. My most resilient roses are a rambler called red buttons, and a ground cover rose called baby blanket. I don't even do anything with them except cut them back. They are in my back yard with the fruits and vegetables so they are not sprayed. There is no light back there but the rose beetles will go after the beans first.

I plant my other roses near the street light. It keeps the beetles away. Garlic chives, and chives planted around the roses are not eaten, they are there for protection. If I do have to spray the flowers from the other plants nearby have to be removed for about 3 months to preserve the beneficial insects. Roses are difficult to grow organically.

For prevention you do have a choice. Fungal diseases crop up when the humidity is high, usually 1-3 days after a long rain and the ground starts steaming up. If the temperature is not over 90 you can either do preventive sprays with an oil, like neem or spray with sulfur. Pick one or the other, you cannot do both. They work best at prevention, they are not as effective as a cure and they only work on the surface of the leaf and don't really affect fungi very much once they have dug into the leaf. You will have to repeat spraying every 3-7 days as long as the weather is warm and humid. Remove any infected leaves and buds, and make sure they are bagged and trashed or the spores will continue to spread.



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