Thrips are slender, tiny insects (generally 1 mm or less) that often have fringed wings. Nymphs lack wings, are elongate, and range in color from off-white or yellow to brown or black. Some common names for thrips include thunderbugs, storm flies, thunderblights, storm bugs, and corn lice. Most thrips feed by sucking out cell contents of leaves or flowers, but some cause leaf distortions or “galls” where they continue to feed and lay eggs. Thrips may cycle through several generations per year so these pest outbreaks can be very damaging. Additionally, the insects may be carried great distances by the wind, and under certain conditions many species can travel in swarms.
Initial feeding symptoms on leaves appear as pale spots from the piercing- sucking mouthparts. At times, black feces will be present next to whitish feeding scars, and this sign will help distinguish damage caused by aphids that do not leave hard fecal matter. Certain species that cause galls, such as Myoporum and Cuban Laurel Thrips, can cause all of the new growth to appear tightly rolled or pod-like at branch tips.
An IMA-jet treatment early in the life cycle of thrips is very effective and provides season-long control. IMA-jet treatment will stop feeding activity within one to two days for common leaf-feeding thrips. For gall-forming thrips, use the highest rate of IMA-jet as soon as possible in the spring to encourage thinning to assist in the removal of infestation centers.
Late Season Control Options
Later season infestations or higher populations that require rapid control respond well to ACE-jet unless growing conditions extend more than 60 days. In this case, a combination of ACE-jet followed by a low- medium rate of IMA-jet will provide good control. In the case of chemical-sensitive areas, the use of Eco-Mite Plus™ and AzaSol™ will provide suppression on a two-week application schedule.
Help Create Ideal Conditions
Generally, the best seasons for injection are spring and fall since uptake occurs when trees are transpiring. The environmental conditions that favor uptake are adequate soil moisture and relatively high humidity. Hot weather and/or dry soil conditions may slow translocation of product into foliage so water trees before and after treatment application. The addition of a soil surfactant, such as NutriRoot, as a drench or sub-surface soil injection will encourage water to move deeper into the soil and increase moisture availability to the tree over time.