Brown lawns can spell trouble when the general assumption is drought is the cause. While dry soil and heat exposure can certainly result in tan or brown grass; disease and insect infestation can mean an unpleasant surprise. I have been seeing extensive second generation chinch bug damage in NH and VT lawns in 2013. In some cases, the scope of the damage has been magnified by a population explosion which began in 2012. Without proper diagnosis and action, chinch bug populations build exponentially month by month with two generations per year in most locations. Since 2012 was so hot and dry, many assumed the browning in their lawn was the result of harsh weather. While this may have been true in many cases, some browning masked chinch bugs. If your lawn is brown now with an abundance of rain, you might have an insect and or disease problem. Without looking up close, this small insect is difficult to identify. A small pocket of chinch bug damage in your lawn can be as small as your fist or hand, while larger infestations can move like locusts across your lawn devouring a half acre or more over months. I have seen both ends of the damage spectrum and everything in between over the last month. Generally, you treat for chinch bugs because left alone, they will simply overwinter as adults, and start over again next spring; building in size and eating power with each successive generation. The math is simple; a lawn treatment spraying for chinch bugs is much more cost effective than thousands in a lawn repair or renovation.
While chinch bugs may reign supreme as surface lawn destroyers, disease can also pop up quickly with humid and warm weather. Several diseases which can cause fast browning and turf loss are brown patch and pythium. Like most fungal diseases, temperature and moisture are critical factors and can influence the likelihood your lawn will become infected. Warm temperatures overnight, usually between 60 to 65 degrees and moisture due to an evening or late afternoon thunderstorm are a perfect storm for pythium and brown patch. Ryegrass is especially susceptible to pythium fungus, a fast moving disease that usually kills grass when it appears. Pythium damage can be seen as sunken, greasy, waterlogged patches of grass which appear matted. Brown patch is best identified by lesions on the leaf blade with a tan interior and a brown or yellow perimeter. Brown patch can appear as small blotches or patches up to several feet in diameter.
While fungicides can be helpful, best results are achieved proactively versus reactively and even then there is no guarantee. Most fungicides only last a week or two under ideal conditions and if you look at the past weather this summer, an ideal spray program would equate to 4-6 proactive treatments; bordering on a golf course regime! Your best bet to combat both pythuim and brown patch is to mow high (3”), mow when the lawn is dry, and use slow release fertilizers in the summer at reduced rates. Run your irrigation only in the morning and keep the cycle deep and infrequent. You can kill your lawn with kindness by watering too much or watering every day regardless of the weather. A lawn with wet feet overnight is an ideal candidate for contracting brown patch or pythium. If your lawn does contract brown patch, it may recover on its own depending upon the severity but some turf thinning is likely. If your lawn succumbs to pythium, often reseeding or over seeding is the only solution in the fall to replace dead grass.
The weather never ceases to amaze me when it comes to throwing curve balls during a given summer. While 2012 was one of the hottest and driest on record, 2013 may go down as the wettest and most humid! Don’t let your lawn head into winter damaged; fall is the best time to fix things before 2014. Aeration, over seeding and or lawn repairs are relevant and appropriate turf improvement services offered by your local lawn care professional. Don’t despair, school starts soon!