With cooler-than-normal early summer temperatures in California, most growers in the state have felt a respite from mites in their vineyards so far this season. The month of May served record-breaking low temperatures and rainfall, according to The Washington Post, postponing pest populations that thrive in hot, dry conditions. Since then the forecast has flipped, and California is experiencing heat in the triple digits. This intense heat is ideal for mites that, unfortunately, will soon populate fast to make up for the late beginning. Due to the abrupt shift in temperature, farmers can expect a tighter-than-normal period of high mite pressure this year.
Many late-season mites, such as the Pacific spider mite, thrive in hot, dry temperatures. As temperatures increase, so too can mite populations. The well-known Pacific spider mite, or Tetranychus pacificus, has become one of the largest threats to high-quality crops, according to University of California IPM. The primary pest mite species for grapes in the San Joaquin Valley, the Pacific spider mite appears early in the season but thrives in the hot, dry months.
The adult Pacific spider mite usually has two larger spots toward the head and two spots toward the rear. The bodies vary in color. Females begin the season colored amber to greenish but can turn orange to red later in the season. Larger than other spider mite species, the Pacific spider mite can also be distinguished by its red forelegs.
With mites, it is critical for growers to act fast. Spider mite populations grow fast to fit their short life cycle. Females can lay up to 10 eggs per day and more than 200 during their lifetime according to the Pacific Northwest Pest Management Handbook. Mite populations are accompanied by webbing and skins from previous molts, as well as a speckling and yellowing of leaves. The pests suck the nutrients out of the leaf cells, causing extensive damage and reduced yield.
UPL provides miticides with quick knockdown, long-lasting control and selectivity on beneficial insects and predator mites, all for excellent IPM compatibility. Products such as VIGILANT®, ACRAMITE®, KANEMITE® and OMITE® Miticides offer protection designed specifically to ward off harmful species. Gentle towards beneficial insects and predatory mites, these miticides work together with the vineyard’s natural ecosystem to keep grape vineyards pest-free.
VIGILANT and ACRAMITE Miticides can be applied throughout the season, offering rapid knockdown and long residual control of all stages of spider mites. Easy on beneficial insects and predatory mites, these products are ideal for integrated pest management programs.
Another treatment beneficial in resistance management is KANEMITE Miticide, which offers a unique chemical subgroup for fast knockdown of all stages of spider mites. With a 7-day pre-harvest interval, KANEMITE is a great option to control two-spotted spider mites and Pacific spider mites towards the end of the grape-growing season.
OMITE Miticide is a great rescue treatment as it features three routes of entry into the pests — contact, residual and inhalation. The product features a unique active ingredient with fuming action that penetrates the webbing and nooks and crannies where spider mites live. Rainfast after drying, OMITE provides long residual control throughout the season.
No matter how growers choose to control spider mite populations, it is important to catch the issue as early as possible and stay on top of it. Grower action now will help prevent damage, protect yields, and reduce the number of overwintering female spider mites, which could damage crops next season.
For a complete line of grape protection and a staff dedicated to keeping your vineyard running strong, contact your retailer or UPL sales representative for additional information, or visit the company website.