Rhododendron Blight (Phytophthora)
Laura Bunton, Austin, Texas
During the early Summer months the persistent fungus die back attacked my rhododendron and azalea plants. I was at a loss as to what was wrong, every week or two several limbs would lose their leaves and die back. I finally had the trouble diagnosed and have learned much during the past season, mainly from experience though, which is always quite expensive.
I immediately inaugurated the prescribed spray program, using Fermate, and can report that it will afford complete control. Dr. Hume recommends yellow Cuprocide, so I will use it immediately after my rhododendrons and azaleas bloom next year.
I presume that this fungus never attacks plants in the Northwest due to the cooler, less humid temperature. Our weather did a sudden drop in temperature in January and then the hottest Summer in many years with very high daily humidity.
I am sure that I could have saved my large plant of R. thomsonii from attacks of this fungus by spraying. The plant began to show a noted loss of leaves as soon as the warm weather progressed and after several months was quite dead.
All the plants that were sprayed with Fermate are in wonderful condition. The Summer also was quite a test of endurance for the plants. The temperature was always 100°F and some days 103 to 104 degrees. All the plants were in full sun from eleven to twelve o'clock, but none wilted or showed any burned foliage. I actually think they withstand dry air better than my azaleas. My old rhododendron Roseum and others are still doing fine after years of these conditions, so I do feel that we can grow rhododendrons successfully here.
I am most firmly convinced that the average gardener here in Texas can grow rhododendrons, where it had been considered impossible before, if a spray program is carried out at the right season. I hope The American Rhododendron Society will publish this letter with my experiences, for I am sure rhododendrons could and should be grown in the South where dismal failure has been the result.
All my other rhododendrons are doing very well and I am anticipating some lovely bloom in March and April. The azaleas have also been attacked by die back but, have responded to the spray very nicely.
EDITORS NOTE. In, the January 1948 issue of the A. R. S. Bulletin, Laura Bunton of Austin, Texas, related some very interesting experiences with rhododendrons and maintaining soil acidity.