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SYSTEMIC, TRANSLAMINAR & CONTACT INSECTICIDES
Systemic insecticides are absorbed by the roots or leaves and then translocated to other parts of the plant. They move upward from where they were first taken up, but they don’t usually move downward. There are a few exceptions, such as Movento HL and Vydate C-LV, which are fully systemic and can move both upward to the leaves and downward to the roots. Neonicotinoids (Group 4A) are a widely used class of systemic insecticides (e.g., Admire Pro, Actara, Cruiser, Platinum 75 SG).
TIP: The ability of systemic insecticides to move to new leaves can be an advantage over contact and translaminar insecticides that must be reapplied to protect new growth. Of course, the advantage is mainly in the early part of the season when potatoes are in the vegetative growth stage.
Translaminar insecticides penetrate leaf tissues but don’t move within the plant’s vascular system. Spinosyns (Group 5) are widely used translaminar insecticides (e.g., Blackhawk, Delgate WG, Entrust SC, Radiant SC). Other translaminar insecticides used on potatoes are Agri-Mek, Fulfill, Carbine 50 WG, and Sefina.
TIP: Systemic and translaminar insecticides can help control insects found mainly on the underside of leaves, such as aphids and potato psyllid nymphs, where contact insecticides may not adequately distribute.
Contact insecticides stick to plant surfaces and don’t get absorbed into the plant. Pyrethroids and organic pyrethrins (Group 3 and 3A) are contact insecticides (e.g., Asana XL, PyGanic, Mustang Maxx, Warrior II). Some other contact insecticides used on potatoes are Aza-Direct, Lannate LV, Rimon, and Torac.
TIP: Coverage is an important consideration for any insecticide, but it’s essential for contact and translaminar insecticides. Pay attention to the use directions related to coverage, such as recommended methods of application, the amount of water to use for application, and the inclusion of adjuvants (stickers, spreaders, or penetrators).
Do’s & Don’ts
Dos:
- Use a neonicotinoid at planting to manage early-season pests such as Colorado potato beetles and aphids.
- Know insecticide product IRAC (Insecticide Resistance Action Committee) codes. The IRAC code denotes the mode of action. Some products have more than one IRAC code.
- Scout early and often for insect pressure, and consider factors that influence insect pressure, including seasonality, temperature, previous chemical applications, and nearby plant hosts.
Carefully read the insecticide product label and pay particular attention to notes about usage, including timing, mixing, and application methods, because they can make a big difference for efficacy. Use the recommended adjuvant for the product you are applying (as indicated on the label). Adjust the pH of the spray solution when recommended by the label. Ensure the products in your tank mix are compatible before mixing them, and always follow the recommended mixing order.
Don’ts
- Don’t use a foliar neonicotinoid (IRAC 4A) if another neonicotinoid was used at planting. This includes neonicotinoid insecticides that are in package mixes.
- Don’t make more than two consecutive applications of products with the same mode of action (same IRAC code) before rotating to a different mode of action.
- Don’t use calendar-based spray programs.
Don’t use pyrethroid insecticides (IRAC 3) from mid-June to a few weeks before harvest to preserve beneficial insects.