As summer approaches, weather conditions may become favorable for whiteflies in Alabama. Vegetable and specialty crop growers are encouraged to begin monitoring fields for potential whitefly activity, despite the common rainfall events of summer across the entire state. Whiteflies, more specifically sweetpotato whiteflies, are tiny, white, flying insect with adults typically around 1 millimeter long. They feed on plant sap, which weakens plants and reduces overall yield (figure 1). More concerning, whiteflies are known vectors for several plant viruses in tomatoes and cucurbit crops, which can completely devastate fields.

The peak of whitefly activity is usually observed from July through October. Hot and dry weather conditions create a favorable environment for a rapid reproduction of the insect. Crops such as squash, zucchini, tomato, cucumber, and cotton are particularly vulnerable. If left unmanaged, whitefly populations can also persist into early winter inside or under protected growing environments, such as greenhouses.

Early Detection is Key

Whiteflies can multiply quickly, making early detection critical. Alabama Extension specialists recommend that growers closely inspect the underside of leaf surfaces for the presence of eggs, nymphs, and adults, especially during warm, dry periods when whitefly populations are most active. Monitoring fields regularly allows growers to make timely management decisions before populations surge out of control.

Taking proactive steps early can help protect yields and limit the spread of plant viruses. Recent studies have identified effective cultural practices that can help Alabama growers manage whitefly infestations. Using silver, reflective plastic mulch significantly reduced whitefly populations compared to traditional white plastic mulch. Also, early season use of row covers delayed whitefly colonization and lowered overall insect pressure. However, insecticide spraying programs are still the best option for growers to keep their fields clear of the insect.

In general, nonchemical strategies serve as valuable tools for Integrated Pest Management (IPM) programs. Incorporating cultural controls, silver, reflective plastic mulch, and the rotation of insecticides with distinct modes of action minimizes selection pressure on pest populations, thereby decreasing the likelihood of resistance development, supporting a more sustainable crop production system.

For more information on whitefly management, or to request assistance with field monitoring, contact your county Extension office at aces.edu.

Featured photo credit: John C. French Sr., Retired, Universities: Auburn, GA, Clemson and U of MO, Bugwood.org