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Isn't this a little contradictory?

Posted by cadence 8b (My Page) on
Thu, Jul 3, 14 at 3:28

I read so many times on this forum not to to get the leaves on your roses wet because you might end up with black spot. (the rose I mean) Yet, it you get aphids on your roses, everyone says to hose them off. They get wet when it rains too. So help sort this out for me please?


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RE: Isn't this a little contradictory?

It's not a warning to NEVER wet the leaves of a rose, as it is to be careful of when. Allowing them time to dry off before the cool of the night comes in is what you should keep in mind. There is a wonderful article in the Michigan Gardener E-magazine this month on watering by one of my favorite gardening guru's, Janet Macunovich. She says in part:
"Another thing we hear often is that we should water early in the day, not in the evening, so leaves can dry off before night and be less susceptible to disease. This makes sense, reducing the amount of time that fungus-prone leaves are covered in fungus-promoting films of water, but then how does Mother Nature get away with evening and nighttime watering? Thunderstorms and rain showers come when they will, yet the normal state of being for plants in the wild is one of good health�"maybe a bit of fungus here and there, but life-threatening epidemics as seen in rose gardens are rare.

If water is applied deeply and occasionally to supplement rain�"perhaps weekly or bi-weekly�"time of day is not so critical as in an every-day automatic system. Occasional watering means occasional openings for fungus infection. Daily late-day watering increases the chances of fungus infection by a factor of seven or more."

if you'd like to read the rest of her informative article on watering your gardens, follow the link.

Here is a link that might be useful: Janet's Journal: Proper Watering


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RE: Isn't this a little contradictory?

There was a study (which I didn't save the link to and thus can't quote) but it suggested that vigorously washing the foliage rinses off BS spores and actually reduces the incidence of fungal disease. Like annececilia said, wash them in the morning so the foliage can dry quickly.


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RE: Isn't this a little contradictory?

Leaves have to stay wet for 8-12 hours continuously for blackspot to germinate.


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RE: Isn't this a little contradictory?

It is standing water that is the problem. Rain is constantly moving and washing away. If one sprays for aphids, etc., usually (usually) the leaves dry quickly. In the case of overhead watering at night, it might not be warm enough for the leaves to dry quickly, so the water sits on the leaves until the sun comes up, or gets warm ehough to dry, etc.

Thanks for the article annececilia!


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RE: Isn't this a little contradictory?

  • Posted by seil z6b MI (My Page) on
    Fri, Jul 4, 14 at 0:10

I've read about the study Cecily brought up. I've tried it myself and I do think that washing my roses with a hard spray of water about once a week has actually helped to hold down outbreaks of black spot for me. And I think it makes sense that rain during the night isn't the same kind of problem that a sprinkler going off in the middle of the night would be. But realistically black spot is just out there everywhere and if the conditions are right for it it will show up no matter what we do. Unless you are willing to spray religiously on a schedule you'll probably have it. You have to decide for yourself if you're willing to do that or if you can live with some not so perfect leaves from time to time. I've learned to stress less about the spots and enjoy the blooms more.


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RE: Isn't this a little contradictory?

" I've learned to stress less about the spots and enjoy the blooms more."

Wise lady! Kim


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RE: Isn't this a little contradictory?

Thanks everyone for all your helpful information. I've learned so much from each of you. annececilia ~ That was a very informative article by Janet Macunovich. Thanks for sharing it with us. I think the most important thing is to water in the early morning giving the leaves time to dry during the day. Thanks again.


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RE: Isn't this a little contradictory?

Thank you for the article. I often do not read articles from zones that are not near mine because I think they may not be relevant. This is relevant for everyone, especially me.

One thing that has not been mentioned is there can be fewer incidents of black spot if you grow roses that don't black spot for other people in your area. That sounds very trite, but I think it is true.

Cadence, my zone is 7A, yours is 8B. Once it gets hot, I don't think it hurts to spray whenever you please. The water seems to penetrate or evaporate quickly.

As far as aphids go, I have difficulty with the hard spray of the hose on the buds. I prefer to put on a glove and wipe them off. The hard spray goes all over the place, and the target buds flop around and are hard to control.

Sammy


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RE: Isn't this a little contradictory?

  • Posted by seil z6b MI (My Page) on
    Fri, Jul 4, 14 at 15:51

Thank you, Kim! I learned a lot from you!


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RE: Isn't this a little contradictory?

You're welcome ma'am! Thank you! I'm glad! Happy Fourth! Kim


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