Benjamin Phillips, Michigan State University Extension; and Mary Mary Hausbeck, Department of Plant, Soil and Microbiology Sciences, MSU-May 1, 2019
Chlorothalonil (Bravo / Echo / Equus) is a FRAC M5 fungicide, known for being easy to use as a stand-alone product or as a tank mix companion, and can prevent many vegetable pathogens. Some examples of chlorothalonil fungicides used to control diseases include tomato ryegrass leaf blight and fruit rot, tomato late blight, tomato anthracnose ripe fruit rot, cercospora and/or brown leaf and celery petiole blight , Alternaria alternata and cut cercospora leaves and petiole carrots, purple spots on white asparagus, purple spots on onions, garlic and leeks, and Alternaria alternata on cucumbers, pumpkins, pumpkins and melons. In addition to these disease examples, chlorothalonil also serves as an important tank mix partner and can be used as a fungicide against downy mildew. Due to its multiple modes of action, the product can be used repeatedly and sequentially.
In times of shortage, other fungicides can be used, and other fungicides can be selected to ensure that vegetable crops are protected. The Michigan State University Extension Department recommends that you pay attention to the FRAC code when deciding to use another broad-spectrum fungicide.
Mancozeb is available as Manzate or Dithane. It is a broad-spectrum FRAC M3 fungicide with similar effects to chlorothalonil. It can be used to fill many gaps that may cause problems due to the shortage of chlorothalonil. Unfortunately, the mancozeb label lacks some crop registration information, including Brussels sprouts, carrots, broccoli, celery and leeks. Similarly, the pre-harvest interval for mango is a relatively long 5 days, which may make it difficult to use for fast-growing and multi-harvested crops such as cucumber, summer squash and summer squash. Due to its multiple modes of action, the product can be used repeatedly and sequentially, but some formulations can only be used for asparagus four times at most and vine crops for eight applications at most.
Switch is a broad-spectrum topical system fungicide that is a combination of fludemonil (FRAC 9) and ciprodinil (FRAC 12). It is active against Alternaria leaf blight in carrots, Alternaria leaf spots in broccoli, Brussels sprouts, cabbage and cauliflower, crater rot in celery, and purple spots in onions. It has a pre-harvest time interval comparable to that of chlorothalonil. In rape, carrots, celery and onions, chlorothalonil can replace chlorothalonil. Its label is limited to leafy vegetables and root vegetables. After using the Switch twice, please rotate it as a fungicide representing another FRAC code, and then use it again
Scala is a broad-spectrum systemic fungicide made from azoxystrobin (FRAC 9). It lacks labels for rape, vines, and asparagus. However, it can replace the purple spots in garlic, leeks and onions. It has a post-harvest interval similar to chlorothalonil.
Tanos is a broad-spectrum, local systemic and contact bactericide, a combination of famoxalone (FRAC 11) and cyclophenoxy oxime (FRAC 27). It is very helpful in controlling Alternaria alternata and has been used as a tank mix with specific downy mildew fungicides. There are no labels for asparagus, broccoli, Brussels sprouts, cabbage, carrots, broccoli or celery. It can be used for all vines, tomatoes, peppers, onions, garlic and leeks. In most cases, the time interval before harvest is shorter than that of Mancozeb products, but for vine crops, tomatoes and peppers, the harvest interval is still three days longer than that of chlorothalonil products. If used repeatedly, the products in FRAC 11 have a higher risk of anti-pathogens. When using Tanos in a spraying program, always rotate it to another FRAC code.
Pristine is a broad-spectrum, local systemic and cross-layer bactericide, which is formed by combining the bactericides FRAC (FRAC 11) and Carboxamide (FRAC 7). Currently, it is not labeled asparagus, canola, tomatoes, peppers and potatoes. It can be used in place of Bravo for Alternaria leaf blight in vines and carrots, Alternaria leaf spot in celery, and purple spots in garlic, leeks and onions. The interval before harvest is similar to that of chlorothalonil. The maximum application limit for vine crops is four times a year, and the maximum application limit for onions, garlic, and leeks is six times a year. Pristine is only allowed to be used in celery twice a year. In the spraying procedure, always keep away from FRAC 11 products every time you use Pristine.
Quadris / Heritage, Cabrio / Headline or Flint / Gem are broad-spectrum topical system FRAC 11 fungicides. These strobilurin-based fungicides have been labeled for use in most vegetable crops, and in most cases the pre-harvest interval is 0 days. These products have a good history of treating many fungal diseases. However, FRAC 11 cone globulin has a high potential to produce drug-resistant pathogens through repeated use. In order to protect the use of strobilurin and delay the development of resistance, current labels limit the number of consecutive administrations allowed in any one year. For most crops, Quadris / Heritage only allows two consecutive applications, Cabrio / Headline only allows one continuous application, and Flint / Gem only allows four maximum applications.
Table 1. Comparison of broad-spectrum fungicides for the most common vegetables grown in Michigan (view pdf to print or read)
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