For douglas fir, loblolly pine and slash pinte, use 3 fl oz/gallon of water.When treating irises, increase use rate to 2 fl oz/gallon of water.When treating azaleas, mountain laurel or rhododendrons, begin spraying when flowers start to show color.If Black spot is not a problem, a 10- to 14-day schedule is recommended. Treat roses on a seven- to 10-day schedule.Apply once every two weeks throughout the season or until conditions favoring disease development (hot, moist weather) are no longer present. Apply to the point when spray just begins to run off the leaves.
There are numerous cultural controls for this diseases, including removing diseased leaves, using clean straw or other mulch around the plants, using cages/other methods to keep plants off the ground, and spacing plants to allow for good air movement.Īpplying a copper-containing fungicide or chlorothalonil will also help prevent disease problems.Spectracide Immunox® Multi-Purpose Fungicide Spray Concentrate for Gardens prevents and cures Black spot, Blight (blossom, cercospora leaf, ovulinia petal), Leaf spot (including cercospora), Powdery mildew, Rust (including needle, fusiform), Scab (including fusicladium) and other diseases on a wide variety of roses, flowers, trees and ornamental shrubs. Early Blight is very similar, except that instead of small black spots, you see 1/2″ lesions with concentric circles (bull’s eye) on the leaves. The disease moves up the plant as the summer progresses. The spots generally appear on the lowest leaves first, causing the leaves to turn yellow and die. If you click on the picture, you can clearly see the tiny black spots all over the leaves. This tomato leaf shows classic symptoms of Septoria. We haven’t seen any sign of them yet, but the symptoms and signs will probably start showing up after this warm, moist spell. Septoria Leaf Spot and Early Blight are two extremely common tomato diseases in this area. As the temperature climbs to 90 or hotter, it takes 12 hours of leaf wetness for infection to occur. At temperatures between 70 and 85, 6-9 hours of continuous leaf wetness will result in infection.
The fungicides should be sprayed every 7-10 days when the conditions are right for infection.
The best way to prevent the disease is to spray with either a copper-containing fungicide or myclobutanil (Immunox, but not Immunox Plus!). Last year I think we lost half of the grapes to this fungus. This morning I am seeing the first of the green grapes with the spots on them. Last week I saw this leaf with the characteristic lesions. I have already seen some indications of the Black Rot on the grapevines. The two diseases that I will be keeping a lookout for in the Demo Garden are Black Rot on the grapes and Septoria Leaf Spot/Early Blight on the tomatoes. Since our dry spell was broken last week with some damp weather, followed by quite a bit of rain, and now humidity, we are seeing great weather for disease problems!
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