How Timerite® Works

Timerite® works by targeting RLEM at a time in their lifecycle when they are most susceptible and at a time of year when it minimises the damage to pastures the following autumn.

RLEM Lifecycle

RLEM is active in the cool wet months from May to November. During the winter, RLEM pass through 3 generations on average, with each lasting about 8 weeks. The first 2 winter generations of mites lay eggs singly, usually on the under surface of the leaf of host plants.

During the 6 hotter months of the year RLEM avoid the hot dry conditions by developing a resting stage which is impervious to heat and drought. They do this by producing diapause (over-summering) eggs in spring. Very high numbers of over-summering eggs are found on the soil surface. Over 100,000 eggs/m2 may be waiting to emerge in the following autumn, providing a threat to the germinating pasture or crop.

In the spring the mites stop laying eggs on plants and start producing the over-summering eggs which are retained in the body. The mites die and the eggs spend the summer in the cadavers (dead bodies) of adult female mites on the soil surface, where they look like grains of sand.

Why The Lifecycle Is Important

RLEM eggs are impervious to pesticides. Therefore, to achieve good control of RLEM there needs to be a minimum of eggs and a maximum of live mites. Timerite? targets a time in the lifecycle of RLEM when this happens.

CSIRO conducted surveys of RLEM in the field. Mites were collected weekly in the spring from 58 sites in southern Australia over several years. From each site, each week, the proportion of eggs that were diapause eggs in 100 females were determined by dissecting the mites, and this was plotted against time.

The date at which 90% of all eggs at a site were diapause eggs was estimated. The period between 10% diapause eggs and 90% diapause eggs was very short, typically 2 weeks.

Timerite? targets the time at which a minimum of both winter and diapause eggs are present, ensuring optimal control of adult mites. This date is exactly two weeks before the date at which 90% off eggs are diapause eggs.

These dates were very similar at each site across years, but varied between sites. The onset of diapause seems to be correlated with a change in day-length and a correction for long-term length of growing season.

Spraying on this date is very important because spraying too early means that too many winter eggs will still be present and survive the spray to go on and hatch and produce diapause eggs. Spraying too late means that diapause eggs will already be present and be able to emerge from diapause the following autumn to attack pastures and crops.

The Importance of a Spring Spray

RLEM cause a significant amount of damage to annual pasture and crop seedlings in autumn. When the RLEM emerge out of diapause is the time at which the seedlings are highly susceptible. This can result in significantly reduced pasture productivity throughout the year.

However, determining when to spray in autumn is very difficult to predict, because the timing of the emergence of the mites is not easily predicted. Once RLEM are observed in the field they can already have caused a significant amount of damage.

Timerite? works at controlling the amount of RLEM emerging in autumn by minimising the number of diapause eggs being produced and therefore the number of mites emerging from diapause.