All my roses are infected with fungal disease

Zone Hot in summer. At present in mid to high 30s but will get to low to high 40s as summer progresses. t | Elaine Glenie added on December 26, 2013 | Answered

All my roses are infected with what I think is a fungal disease. The leaves turn brown starting from the outside of the leaf until whole leaf is brown & falls off. I have sprayed with many different fungicides, including trueforte, to no avail. I water every day. The temp here is in mid to high 30s at moment but will be in low to high 40s in later summer. Am I overwatering too much? Is Neem oil any good?

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Certified GKH Gardening Expert
Answered on December 29, 2013

The foliage on some rosebushes can be very sensitive to some of the chemical fungicides so it could be chemical foliage burn. It can also be, with the lower temps, a bit of Jack Frost biting the foliage. It shows up first at the outer edges of foliage and blooms, then creeps inward. It may be just a natural thing with the weather conditions and not really much can be done about it. The roses try to go dormant in the cooler to cold temps every year, it is their rest period so that they can come back with new vigor in the spring. I use a fungicide called Green Cure that is available on-line and at some local garden centers. Never have had any issues with leaf burn using it either. It does not sound like an overwatering problem, unless the water is allowed to remain upon the foliage during the hotter times of the day. In such a case the water can act as a magnifying glass that will concentrate the suns rays and burn the foliage.

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