Almond and pistachio growers have adopted some new production practices in recent years in an attempt to maximize yields. Unfortunately, higher planting density, longer and more frequent microsprinkler irrigations in the humid Sacramento Valley and a shift to more susceptible nut varieties provide ideal conditions for the development of diseases such as Alternaria leaf spot (almonds) and Alternaria late blight (pistachios).
Alternaria has become much more important than it was 10-15 years ago. Left unimpeded, Alternaria will defoliate an almond tree prematurely and at the expense of next year’s crop.
Quash® Fungicide from Valent U.S.A. Corporation is a highly effective and top-rated triazole chemistry that controls a broad spectrum of tough diseases throughout the season. When applied preventively for control of Alternaria post-bloom, Quash helps keep leaves on trees until normal leaf drop in the fall, allowing trees to preserve energy for next year’s crop rather than flushing early in response to disease.
While Alternaria leaf spot has shown resistance to QoI (strobilurin; Fungicide Resistance Action Committee – FRAC – Group 11) and SDHI (FRAC Group 7) fungicides in the Sacramento Valley, there are no resistance issues with Quash. Also, unlike many of the commonly used premixes that may include, for example, a strobilurin, Quash offers a single mode of action and thus offers a flexible fit in resistance management programs.
The ideal application timing for Quash on almond Alternaria leaf spot is in May and June. For leaf rust, another increasingly important almond disease that can lead to defoliation, Quash should be applied about five weeks after petal fall and then again four to five weeks later in May.
Quash also controls other tough, post-bloom almond diseases such as anthracnose and scab.
Similar to Alternaria leaf spot in almonds, Alternaria late blight is a disease that adversely affects pistachio crops. The combination of high humidity and leaf wetness stemming from frequent irrigation and morning dew provides an ideal environment for Alternaria late blight, which stains shells and can lead to mold on kernels and premature defoliation.
For optimum control of pistachio Alternaria late blight, apply Quash in June and July with a two to three week interval between sprays.
Quash also provides excellent control of other key pistachio diseases, including Botrytis blossom and shoot blight and Botryosphaeria panicle and shoot blight. Begin treating for these diseases in April.
To learn more about Quash and the rest of Valent’s portfolio of tree nut products, visit www.valent.com/quash.