Question: How can I control aphids, psyllids and Colorado potato beetles while still maintaining my beneficial insects?

{Sponsored} Many potato farmers use pyrethroid insecticides for a variety of reasons. However, repeatedly using broad-spectrum insecticides has set farmers up to have infestations of secondary pests such as spider mites. It also increases the likelihood of aphid, psyllid and Colorado potato beetle populations developing resistance to these chemistries.

Since new insecticides are not frequently introduced to the market, it is imperative that we use the tools we have, appropriately, to avoid resistance development. With many different types of insect pests, potato growers need to use all of the tools available. Products like Beleaf® 50 SG insecticide (for psyllids and aphids) and Exirel® insect control powered by Cyazypyr® active ingredient (for aphids and Colorado potato beetles) should be a part of that arsenal.

Farmers must control aphids, psyllids and Colorado potato beetles to prevent disease development and subsequent crop damage. When infestations of these insects occur, diseases can be vectored. For example, aphids can vector leafroll virus (which results in net necrosis of tubers) and potato virus Y, while zebra chip can be transmitted by potato psyllids.

Aside from a decrease in yields associated with reduced plant productivity, farmers can face losses from the internal defects associated with the insect-vectored pathogens. At a certain level, growers receive less value per ton of potatoes, and with high levels of internal defects, they face rejection of the field. So, those issues go from being somewhat economic to severely economic.

Resistance to insecticides can develop rapidly when the same product is applied multiple times during the growing season. Resistance occurs when some insects in the target population carry a mechanism that makes the specific insecticide ineffective at controlling those individuals. Every time that specific insecticide is applied, it increases the proportion of resistant individuals in the population until that product no longer controls the pest effectively. Additionally, using broad spectrum products can dramatically decrease a farm’s beneficial insects. Reducing beneficial insects typically results in infestations of pests such as spider mites, which are also hard to control, and may cause significant losses if they get out of hand.

The Pacific Northwest has some advantages in this fight. Farmers in the region are not only rotating crops to prevent resistance, but they are also very careful about pesticide selection such as only using neonicotinoid insecticides once per season. They’re employing proper rotation of insecticides to prevent resistance and applying the right products to manage targeted pests. Secondly, they are cautious not to apply pyrethroids from the second week in June until close to harvest to avoid secondary pest outbreaks.

Farmers’ best results for controlling pest insects will happen when they rotate insecticides with different modes of action to avoid resistance, avoid broad spectrum insecticides, rotate crops and use selective insecticides that help conserve beneficial insects.

Beleaf 50 SG insecticide and Exirel insect control are unique. Beleaf 50 SG insecticide is the only group 29 on the market, making it a great tool to avoid resistance development while achieving good control of aphids and potato psyllid. Exirel insect control is not the only group 28, but it has a broader spectrum that controls aphids, psyllids and Colorado potato beetle, while having minimal impact on most beneficial insects. Controlling these problematic pests reduces the likelihood of plant diseases being vectored and improves plant health.

When farmers start to see small populations of aphids, psyllids and Colorado potato beetles, it is imperative that they quickly apply an insecticide that rapidly stops insect feeding and establishment; this can be readily accomplished with Beleaf 50 SG insecticide and Exirel insect control. Farmers won’t find dead insects for a few days with these products, but those insects farmers do see will not be destroying the foliage.

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Always read and follow all label directions, restrictions and precautions for use. Some products may not be registered for use in all states of the United States. The EPA registered label for Exirel insect control contains the following statements: This product is highly toxic to bees exposed to direct treatment on blooming crops or weeds. Do not apply this product or allow it to drift to blooming crops or weeds if bees are foraging (actively visiting) the treatment area. As of November 1, 2017, the USEPA registration for DuPont™ Exirel insect control has been sold by E.I. du Pont de Nemours and Company to FMC Corporation and/or an FMC affiliate. FMC and Exirel are trademarks of FMC Corporation and/or an affiliate. Beleaf is a trademark of Ishihara Sangyo Kaisha, Ltd. ©2018 FMC Corporation. All rights reserved. 03/18 18-FMC-0107

About the Expert: Tim Waters is a regional vegetable specialist and associate professor for WSU Extension. Timothy WatersHe has been stationed at the Extension office in Pasco since 2006 and has responsibility for irrigated vegetable crops in the lower Columbia Basin. He performs outreach and applied research on various vegetable crops including potato, onion, corn, carrots, beans, peas and alternative crops. Recently, he has focused on improving integrated pest management of pests of potato and onion. Tim is an entomologist by training having earned both MS and PhD degrees from Washington State University. “Go Cougs!”


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