Peach leaf curl, also known as leaf curl, is a disease caused by the fungus Taphrina deformans. Peach leaf curl affects the blossoms, fruit, leaves, and shoots of peaches, ornamental flowering peaches, and nectarines, and is one of the most common disease problems for Texas Peaches. The distorted, reddened foliage that it causes is easily seen in spring. When severe, the disease can even reduce fruit production substantially. If you saw leaves that looked anything like the ones above, you may want to consider treatment.
Leaf symptoms appear about 2 weeks after leaves emerge from buds. The fungus grows between leaf cells and stimulates them to divide and grow larger than normal, causing swelling and distortion of the leaf. Red plant pigments accumulate in the distorted cells as you can see in the picture above.
Why am I writing about this disease now since we won’t see it till spring? Well, this disease has gone through the summer and is on the tree now as ascospores (sexual spores) and bud-conidia (asexual spores) on the tree’s surfaces, such as leaves, buds, bark, etc. As we get into the fall and much cooler temperatures or even a frost the leaves will begin to fall off. This leaf abscission (separation of the leaf from the tree) is actually a wound. When you have a wound, you have a place for these disease spores to enter the tree. Any dew, light rain or even wind can move spores to the wound.
So, as the leaves begin falling off or after they have all fallen off, it is time to consider a treatment. Generally, a single early treatment when the tree is dormant is effective, although in areas of high rainfall or during a particularly wet winter, it might be advisable to apply a second spray late in the dormant season, preferably as flower buds begin to swell but before green leaf tips are first visible.
Historically, the most commonly and basically only fungicide for organic growers to use are the fixed copper products (see below for a list). For all copper-containing products, the active ingredient, copper, is listed as “metallic copper equivalent,” or MCE, on the label. Various product formulations differ widely in their metallic copper content. The higher the MCE, the greater the amount of copper and the more effective the product will be. However, other factors such as coverage, use of additives as such stickers and spreaders, and frequency and duration of rain, which can wash off the copper, also will impact product effectiveness. In all cases, the copper is active only when it is wet, when the copper ions are in solution. Thorough coverage is very important but without leaves not that hard. It is really good to get a calm day, lower pressure down, try to get a mist out of your spray tips and make sure the limbs are wet.
|Active Ingredient||Trade Name||Company|
Champ ION or WG
|Copper oxychloride 23.82% |
Copper Hydroxide 21.49%
|copper sulphate (pentahydrate)||Cuproxat|
As I first said, It’s time! It’s time for all you peach growers to get that sprayer back out, purchase your spray product, and SPRAY!