My rose bushes leaves are turning yellow and dying.?

I have several rose bushes that are blooming and look healthy one day, then the next time I look, the leaves are yellow with brown/black spots. The leaves fall off until the bush is stripped completely. The rose bush then leafs out again, and fills in. The rose bush continues to bloom this entire time. I use a rose bush bug spray once a month...I guess it is not working. Any ideas what it is, and how to cure???

My rose bushes leaves are turning yellow and dying.?
Rose black spot, caused by the fungus Diplocarpon rosae, is the most common cause of defoliation of landscape roses.





Symptoms





Fig. 1. Leaf symptoms of rose black spot.


(Photo by R. C. Lambe)


Small, round spots, ranging in size from 1/16" to 1/2" in diameter, appear on the upper sides of leaves. Leaf tissue adjacent to the spot turns yellow. Whole leaves eventually turn yellow and fall prematurely. Black spot can be distinguished from other leaf spot diseases of rose by the generally fringed margins and the darker and consistently black color of the leaf spots. Similar spots may appear on petioles and fruit. Raised, reddish-purple spots may also appear on canes. If black spot is left uncontrolled and early defoliation occurs, bushes are weakened and cane dieback the following spring may be severe. Weakened plants may continue to die even after the plants leaf out.


Cultural Control


A preventative program for black spot should begin in the fall with a thorough sanitation program. Diseased leaves on the ground should be raked and burned or removed. All diseased canes should be pruned back to healthy wood. These practices will reduce the amount of overwintering fungus. During the growing season, overhead irrigation, which prolongs leaf wetness, should be avoided. If plants are overhead irrigated, watering should be done in the morning rather than the afternoon so that leaves dry quickly.


Chemical Control


Fungicides registered for black spot control should be applied preventatively to susceptible roses starting in spring before the new leaves become spotted. From this time through frost, the plants should never pass through a rainy period without a protective coating of fungicide on the leaves. Fungicides registered for black spot control include propiconazole (e.g. Banner), thiophanane methyl (e.g. Cleary 3336), chlorothalonil (e.g. Daconil 2787), mancozeb (e.g. Fore, Dithane, or Maneb), thiophanate methyl + mancozeb (e.g. Zyban), trifloxystrobin (e.g. Compass) and myclobutanil (e.g. Systhane). Most of these fungicides can be sprayed at 7-10 day intervals when rains are infrequent. During rainy weather, it may be necessary to spray the plants more frequently. Details on rates and timing of application can be found the current Virginia Pest Management Guide for Home Grounds and Animals (VCE Publication 456-018) or the Virginia Pest Management Guide for Horticultural and Forest Crops (VCE Publication 456-017), http://www.ext.vt.edu/pubs/pmg/. For information on the proper use of pesticides and fungicides, refer to any current VCE pest management guide.


From http://www.ext.vt.edu/pubs/plantdiseasef...
Reply:i water my bushes by putting the hose on low and leaving it on slow.then i don't water for a week.Real pretty roses all year round.i live in Ca. and it gets hot in summer.
Reply:to much water. the first sign is yellow leaves
Reply:Yikes!It's a black spot infection.It's a fungus that attacks roses-get out the antifungal spray before it's too late.Bug spray won't help.