Learn more about pollen - Plantain

Plantain (Species, Plantago lanceolata; Family, Fagaceae)

Plantain (also Ribweed, Ribgrass, Lamb's Tongue, or Narrow-Leaf Plantain) or Plantago lanceolata, is an annual or biennial herb with lance-shaped leaves. Introduced from Europe and Asia, it is an abundant lawn weed in temperate regions of Australia. They are wind-pollinated and produce large amounts of pollen during October to February.

Next to some of the well-known allergenic pollen types such as Rye grass, Plantain is considered as significant as an allergic pollen in the temperate regions of Australia. There area number of native Plantago species, though these are relatively rare and their allergenic properties are unknown.

 

Distribution of Plantain (Atlas of Living Australia occurrence map)

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Above average rainfall in early November quells an angry Godzilla hay fever season

Predictions of a Godzilla hay fever season in October of this year appeared to be well on track to come true. That is until a period of unusually high rainfall for early November subdued the angry beast. Daily pollen counts for grass in Canberra over the October-November period showed that the early season pollen levels where well above average, however, just after the beginning of November grass pollen levels began to dip below the long term average. So much so that people in Canberra have encountered a total of only 1500 grass pollen grains/m3 across the season this year compared to 2200 grass pollen grains/m3 in 2014. Why did this happen and what can we learn from these observations?

The Bureau of Meteorology reported that the long term average rainfall for Canberra in November (64mm) had fallen entirely within the first two weeks of November. The occurrence of rainfall during the day can have a significant impact on the concentration of hay fever causing pollen by effectively “washing out” these small particles floating in the atmosphere.

The occurrence of high rainfall during the first two weeks of November also coincided with the peak time for grass pollen production in the ACT. This resulted in a significant reduction in the total grass pollen atmospheric load for the season. However, this did not eliminate all allergenic particles as there has been a significant rise in the fungal spore Alternaria during these wetter periods. One of the key lessons from this year is that predicting pollen levels is a tricky thing and will remain highly problematic until we can accumulate multiple years of real data to analyse. 

Top graph shows the cumulative pollen load for Canberra illustrated as the minimum, average and maximum for years since recording began in 2007 (Oct-Dec recording period). The pollen load for 2015 up until the end of November is depicted in red. The bottom graph shows the long term average and standard deviation for an entire year based on historic records of grass pollen in Canberra. High rainfall period (total = 64mm) recorded in first 2 weeks of November 2015.

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Mowing your lawn this weekend? Be aware of the allergenic fungal spores lurking in the grass and soil

Alternaria alternata

Ever wonder why mowing the lawn can bring on hay fever or asthma symptoms? Many people think it must be the grass pollen that is stirred up by the mower. But when you think about it this is highly unlikely given the short stature of lawn grass and, in even moderately maintained lawns, the grasses rarely are able to flower and release pollen before the next mow. The likely culprit causing heightened irritation and allergic responses around lawns, and particularly during mowing, are the microscopic fungal spores known as Alternaria.

The mold Alternaria is a well-recognized allergy causing fungus.  The mold can be found on leaves and stems of plants (including grass) and within soils. Mowing lawns in urban environments and harvesting crops in rural environments can contribute to increasing the abundance of spores in the air. Alternaria spores can be detected from spring through late Autumn in most temperate areas, and can reach levels of thousands of spores per cubic meter of air, particularly during dry, windy conditions, following a period of rain. 

These weather conditions sound familiar? The last two weeks of relatively high rainfall in Canberra, followed by an impending heat wave, has created the ideal conditions for Alternaria to spore and on the 18th November, 2015, we recorded our first EXTREME level of Alternaria alternata in Canberra Daily Pollen count (175 Alternaria alternata particles/m3). These same weather conditions are likely to bring out a lot of home owners wanting to mow their lawn as soon as the fine weather returns. The act of mowing your lawn disturbs a primary site for Alternaria, and in the process may fan large numbers of spores into the air. 

So be aware and take precautions if you are sensitive to Alternaria as there are likely to be very high levels of spores in Canberra’s air over the next few days and especially this weekend.

Clockwise images: Alternaria alternata spore chains; Leaves and stems infected by the mold Alternaria; "dust" created when mowing lawns.

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