In a recent report both creeping bentgrass and couchgrass golf course greens are capable of absorbing urea through the leaf (foliage). However, the efficiency is not consistent varying from 32 to 69 percent for both creeping bentgrass and couchgrass. Most of the urea is absorbed within 4 hours with the greatest increase within the first hour. There were no consistent seasonal trends that could account for the range in efficiency.
The researchers found that as you increased the rate of urea the efficiency decreased. For maximizing nitrogen foliar efficiency uptake by the plant using urea recommendations would include
i) the application rate should be low (<0.5 g N m-2) and
ii) wait several hours to maximize foliar uptake before applying water (irrigation).
Then apply water to wash any unabsorbed urea remaining on the leaf surface into the soil may provide for a second chance uptake by the root system.
Reference:
Stiegler, C.J., M.D. Richardson, and D.E. Karcher. 2011. Foliar nitrogen uptake following urea application to putting green Turfgrass Species. Crop Science 51: 1253-1260
Brown Ring Patch
One disease that has become more prevalent over the last few years is brown ring patch on Poa annua putting greens. This disease has similar symptoms as that of yellow patch. As we have previously discussed with these diseases that yellow patch often occurs under cooler springtime temperatures and often disappears once temperatures warm.
Brown ring patch would often occur after a few warm days (in the high 20s low 30s C). However, brown ring patch is being found increasingly at cooler temperatures. In the northeastern United States it often occurs from Christmas to the end of May then the symptoms disappear.
Brown ring patch is often associated with low nutrition turf. Fungicide applications will control the disease, with preventative applications the most effective. However, often the preventative treatments (multiple applications) are expensive. A curative treatment is effective. In general, the strobilurin fungicides like azoxystrobin (Heritage TL ®) are effective.
Symptoms of brown ring patch on a Poa annua putting green