The nights are cool and humid, the fog is lingering until almost noon, which means it is downy mildew time. Discovered about 8-9 seedlings that had suddenly defoliated, all in bud, none of them yet blooming, with the bud drooping real sadly. So far it is affecting only a few which I have removed. At this point in time I do not want to spray but then again I do not want to see an epidemic!
This is not from this yr., but it is just about what it looked like. Except the seedlings are no longer under the pine trees and they are a lot healthier now, but still susceptible.
This is the only thing that I spray for. If you anticipate conditions to be “right” for dm for more than 1 or 2 more days, I would not wait, but would spray ASAP! I hope that your conditions improve.
Henry, I have not tried Hydrogen Peroxide this year but have tried it previously. it is very hard to know if it was the weather changing or the peroxide that saved a few. I believe I tried it to late. I am checking them AM and PM for any changes. I did use the neem product “Azamax” last year, and the outbreak stopped. It is again hard to say if it was because of the Azamax or the weather drying out and warming up. Fog and AM/PM humidity seems to be becoming a real trend here as of the last few years, as well as cooler nights during that same period. I did check the forecast and the temps are to be in the high 60’s in the day, and high 40’s to low 50’s at night. that does call for some protective spraying. None of the mature shrubs, but maybe one of the yearling seedlings show some symptoms, or pre-symptoms. One of the Gemini’s does have a lot of purply leaf undersides with a droopy look to them, which is suspicious. Well I do know what I will be doing tomorrow.
Hydrogen Peroxide For the Treatment of Dying Seedlings
_One of the frustrations of rose hybridizing is to watch a seedling slowly die. This season I seemed to have found a treatment that appears to have helped in a number of cases. I use an eye dropper to add undiluted commercial 3% hydrogen peroxide to the seedling. I apply the hydrogen peroxide to the top of the seedling and let it run down the seedling into the soil. I am putting the hydrogen peroxide on very small stressed and/or dying seedlings. Some are too far gone to save, others seem to put on a burst of new growth. The hydrogen peroxide could be acting in either of two possible modes: