A slow start to spring has given way to a very hot and dry start to summer for those in Quebec and Atlantic Canada. It has been a challenging summer to maintain high-quality turf in residential landscapes. Already there are a number of water bans in place due to near record drought conditions. This has resulted in a perfect storm for chinch bug populations and the damage they cause.
Chinch bugs are very small insects that overwinter in the turfgrass thatch, leaf litter or other protected sites. As temperatures warm in the spring, the adults will mate and lay eggs in the turfgrass thatch or directly into the folds of the turfgrass plant. When temperatures are below 20°C, it may take 20-30 days for the eggs to hatch. However, if daytime temperatures consistently exceed 25°C these eggs can hatch in just one week. The average female adult can lay up to 200 eggs. This results in skyrocketing populations of adults and nymphs under favourable environmental conditions in early summer.
Early instar nymphs go through several stages before reaching adulthood. However, every stage of the nymph can damage plants through their piercing-sucking mouthparts. In addition, during feeding, nymphs and adults secrete a solution into the turfgrass plant that clogs the vascular tissues. This causes further stress as this secretion helps block the transport of water, leading to the advancement of drought stress.
CULTURAL CONTROL STRATEGIES
IRRIGATION // Where possible, irrigate home lawns to provide supplemental water during drought stress. This promotes a healthier turfgrass stand that can better tolerate chinch bug activity.
FERTILIZATION // Nitrogen fertilization helps provide more energy to the plant to help withstand chinch bug activity and promote recovery during these stress events. Be careful not to over-fertilize as this can also attract more chinch bugs.
PLANT GENETICS // Overseeding more resistant cultivars or species into the mix can help mitigate the damage of chinch bugs. A monostand of the same cultivar of grass is always more susceptible to insects and diseases.
CHEMICAL CONTROL USING TETRINO 43SC AND DELTAGARD
TETRINO™ is a new broad-spectrum systemic insecticide that has strong activity across many root- and surface-feeding insects. Tetrino should be applied as a foliar spray to control surface feeding insects such as chinch bugs. However, it may be important to apply in a sufficient water volume to provide coverage towards the base of the plant. Applications of Tetrino should be made once very small nymphs are observed in the thatch layer. As a systemic insecticide, Tetrino works best when the plant is actively growing.
DELTAGARD® is a broad-spectrum contact insecticide that is effective against chinch bugs and several other surface-feeding insects. Similar to Tetrino, DeltaGard should be applied in a sufficient water volume to achieve coverage deeper into the turfgrass canopy. DeltaGard is an excellent choice in severely compromised lawns when the turfgrass is entering summer-induced dormancy.
CONSIDERATIONS OF CHEMICAL CONTROL
Chinch bug populations can increase exponentially during hot and dry weather. So far, there have been reports of near record populations in nontreated landscapes. As few as 80 chinch bugs per square meter can result in visible damage in residential lawns. This year it has not been uncommon to see reports of 600+ chinch bugs or more per square meter. This means it can be challenging to eliminate all visible damage, even when you are reducing the populations by 90% or more through chemical treatment.
Another consideration is trying to calculate percent control. When we scout for these small insects, our eyes are drawn to moving targets. We only visually observe the alive chinch bugs. It is very difficult to access mortality unless we carefully sift through the thatch layer. It’s hard to see a chinch bug that’s been keeled over on its back for three days!
Lastly, managing chinch bugs has become more challenging in areas that are adjacent to nontreated landscapes. This can result in a daily migration of thousands of chinch bug adults and nymphs moving from nontreated areas into treated areas. Once the concentration of the insecticide wears off, these migrating chinch bugs can move into the treated area and begin to cause further damage and decline.
Moving forward it will be best to continue monitoring the effectiveness of your chemical control program and to communicate these challenges to your clients. If re-applications are necessary, it would be wise to access the health of each of the respective lawns. If the turfgrass is actively growing, then a follow-up application of Tetrino (28 days after the first application) would be beneficial. If the lawn is approaching dormancy, then a follow-up application of the contact insecticide DeltaGard (applied at the high label rate) would be appropriate.
For more information about insect control strategies contact your local Territory Sales Manager.
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