Allergy Season With Spring On Its Way: Turfgrass Growth Rates Increase And Summer Stresses Begin

Spring signals the start of the busy season for many turfgrass managers. Increasing temperatures increase turfgrass growth rates and bring on the summer stresses of heat, moisture, pests and diseases. Spring for many is also the start of the hay fever season, when people susceptible to various plant pollens can suffer severely. A perception is that this allergic reaction is due to spring flowering trees and shrubs, but grass pollen plays a significant role. Monitoring of air pollen counts has shown that grasses can contribute the majority of the pollen load. Many of the grasses involved are important turfgrass varieties. The general assumption has been that ryegrass is the most important allergic grass pollen, but recent research has found the pollen of other grasses can play a significant role.

Dr. Janet Davies from The University of Queensland is an international expert in the research of grass pollen as a trigger for hay fever and asthma. Her research has concentrated on the subtropical grasses. Recent research examined the sensitivity of people in Brisbane to pollen of Bahia Grass (Paspalum notatum), Johnson Grass (Sorghum halepense), Couchgrass (Cynodon dactylon) and Perennial Ryegrass (Lolium perenne). This research found that sensitive people from this region showed greater allergy to Bahia Grass and Couchgrass pollen. It is hoped that more specific treatments to the pollen of these plants can be isolated.

The components in pollen which cause the allergic reaction are a range of proteins. These proteins differ between grasses, with some having a greater range of allergens from different chemical families than other grasses. Related grasses often share similar groups of allergens.

A recent review of pollen counts across Australia and New Zealand found the grass pollen season ranged from 10 months in Darwin (February-November) to 4 months in Perth (September to December), Canberra and Melbourne (both October-January). These are the periods when 90% of the annual pollen count was collected.

Air pollen counts provide important information for allergy sufferers and are done at several locations around Australia. These are done daily during the pollen season. A spore trap collects pollen on a glass slide which is then examined under a microscope and a count made. Results are reported as grains of pollen or cubic metre of air and a classification of risk made as shown in the table.

Information on pollen counts can be obtained from on-line from weather websites like Weather Zone. The Asthma Australia website also has this information. A range of apps also give information on air quality and pollen counts (search “pollen count”). For allergic people these give a pollen forecast and participants can also help with research into how the pollen counts relate to their symptoms.

Common Snot takes hold in Sydney

Recently, golf courses in Sydney reported a gelatinous organism which looks like algae. These have been identified as cyanobacteria called Nostoc commune which is sometimes called “common snot”.

The Nostoc bacteria are different as they are capable of fixing nitrogen from the air. Geologically speaking, they play a major role in soil development and the conversion of atmospheric nitrogen for other organisms. 
Nostoc commune is most commonly seen on newly cleared soil after rain. It’s unknown what conditions encourage its development in turf. Certainly excess rain or irrigation is a factor. When it dries out, it breaks up and the fragments disappear into the soil. 

The bacteria are so large on greens they grow beyond mowing height and affect the smoothness of the turf’s surface, as well as making green preparation difficult. Reproduction involves tiny propagules which are probably moved by water, wind and on mowers.

Nostoc Treatment

Management of this problem has been difficult. Sometimes, the larger masses can be raked and manually removed. To date, various chemicals have provided inconsistent control results. Some fungicides appear to be helping alleviate the problem.

To find out more information, reach out to our team.