Featured Article | GreenCast | Syngenta

Understanding when to water-in plant protection products

By Mike Agnew, technical services manager, Syngenta

To get the best performance out of any product application, there are many best management practices to consider. The focus of these recommendations is to review water movement into the soil, watering depth and product applications. Always check the product label for watering-in recommendations.

The objective of post-application water is to move the product to the source of the problem. This is especially true when controlling nematodes, fairy ring, summer patch and insects such as grubs, annual bluegrass weevils (ABW) and caterpillars.

Nematodes | Fairy ring | Summer patch | Grubs and ABW | Surface-feeding insects
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Nematodes
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Controlling nematodes with Divanem® nematicide is best achieved if Divanem moves into the soil where nematodes are most active. Divanem should always be tank-mixed with a soil surfactant to aid movement through the thatch layer. Applications with Divanem (for both the broadcast and spot treatment rates) are best made to wet turf. If dew is not present, use a short irrigation cycle to moisten the turf prior to application. The first watering-in option for Divanem is to irrigate with 0.25 in. of water within one hour of application. The second option is to irrigate with 0.125 in. of water within one hour after application, and another 0.125 in. of water within 24 hours.

Nematode-damaged roots not only absorb less water, but are also more susceptible to disease. When combined with Heritage® Action™ fungicide, Divanem can further improve turf quality, turf density, root growth and root quality, as well as provide enhanced biotic and abiotic stress tolerance. The Divanem + Heritage Action Multipak contains 0.5 gal. of Divanem plus 5 lbs. of Heritage Action and provides convenience when applying these products together.

For more information about nematode control rates and scouting tips, visit www.GreenCastOnline.com/NematodeKnowledge.

Fairy ring
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For fairy ring control, it’s important to determine the depth of the fairy ring infestation. If fairy ring is limited to the thatch layer, irrigate with 0.1-0.15 in. of water following the fungicide application. If fairy ring is 2-3 in. deep, irrigate with 0.25 in. of water following the application. Tank-mixing with a soil surfactant can facilitate movement of the active ingredient deeper in the soil, especially if fairy ring symptoms are already present. Repeated applications at regular intervals are needed to maintain consistent suppression in the soil.

For best results, Velista® fungicide should be watered-in soon after application. You can irrigate with 0.25 inches of water within one hour after application or irrigate with 0.125 inches of water within one hour after application and another 0.125 inches of water within 24 hours.

Applications of Heritage®, Banner Maxx®, Headway® and Briskway® fungicides can be allowed to dry on the foliage, and then watered-in prior to the next mowing.

For more information about fairy ring control, view our fairy ring solutions sheet.

Summer patch
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Summer patch is a root-infecting pathogen that affects annual bluegrass, Kentucky bluegrass and fine fescues. Since the pathogen is soil-borne, the immediate response is to water-in all fungicide applications. While this is true for Kentucky bluegrass and fine fescue, some caution needs to be taken with annual bluegrass on greens.

Watering-in fungicides like Heritage and Headway in the spring is recommended, as roots are actively growing and will be deeper during this time period. Applying 0.1-0.15 in. of water is often adequate to move the fungicide into the soil. The active ingredient in both products, azoxystrobin, is taken up by the roots for protection. However, during the heat of summer, it is common for annual bluegrass roots to die back.

In this case, apply either fungicide in four gallons of water per 1,000 sq. ft. This will move the fungicide to the surface inch where the active roots reside. If this volume of water is not achievable, water-in with 0.05 in. of water, or no more than a light syringe. If too much post-application water is applied, it may move the active ingredient below the active roots, lessening the fungicide’s protection.

For more information, view this article about application timing, products and rates for protecting turf against summer patch.

Grubs and ABW
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Watering-in recommendations are the same for insecticides. If control is for surface-feeding insects, don’t water-in. It is recommended to water-in products like Acelepryn® and Meridian® 25WG insecticides for white grub control. The key is to target the upper 1 to 2 in. of soil where the insects hatch and develop.

Watering-in requirements for the control of annual bluegrass weevils (ABW) can be more complex and recommendations will vary with the target life cycle and insecticide. For the control of adults, it is not necessary to water-in the insecticide. Pyrethroid insecticides, like Scimitar® GC, should be allowed to remain in the canopy of the turfgrass. If watered-in there is the likelihood that the active ingredient will be moved into the soil, thus reducing the ABW adult control.

For optimal control of larvae, it is generally a good practice to wash the insecticide off of the upper leaf tissue to the crown of the plant. Insecticides like Acelepryn and Ference® are absorbed into the upper root-zone and crown and will move upward in the plant. Watering-in with 0.05 to 0.1 in. of water may improve ABW control. Research has shown that Ference does not require watering-in, however if allowed to stay on the surface much of the product can be removed by mowing and ABW control may be reduced, especially if the application was made to control large larvae.

Provaunt® WDG insecticide is an excellent product for curative control of crown feeding ABW larvae or 3-5th instar. Once applied to the turf, it will move into the cuticle and translaminar across the leaf. Therefore, it is important to water-in immediately with 0.1 to 0.15 in. of water to move Provaunt WDG to the crown of the plant where the ABW larvae are feeding.
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Surface-feeding insects
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When targeting insects that feed solely on the surface (lepidopteran, caterpillars, ants, etc.) watering-in should be avoided for all insecticide applications.

For more information about watering-in, or if you are unclear about whether or not to water-in a particular product after reading the label, contact your local Syngenta territory manager.


©2019 Syngenta. Important: Always read and follow label instructions. Some products may not be registered for sale or use in all states or counties and/or may have state-specific use requirements. Please check with your local extension service to ensure registration and proper use. Divanem and Scimitar GC are Restricted Use Pesticides. The trademarks or service marks displayed or otherwise used herein are the property of a Syngenta Group Company.