Cleavers
Cleavers (Gallium aparine) is a dicotyledonous, or broad-leaved, annual species. At the early seedling stage cleavers produce distinct, large cotyledons with a characteristic notch at the tip. Until the first whorls begin to appear, these seedlings can be confused with those of ivy-leaved speedwell. The adult plant has a very characteristic appearance because of the way its leaves are arranged in whorls running up the stem and the size of the plant as it scrambles across the field using the crop for support. In summer, typically June, numerous tiny white flowers produce pairs of seeds covered in hooked hairs that can attach themselves to clothing or animal fur. Partly because of the size the adult plant can reach, and its ability to climb over the top of the maturing crop, cleavers infestations have the potential to cause very considerable crop losses.
Control Options
There are two priorities for selecting a cleavers control product: final level of control and speed of control. To prevent yield loss and minimise seed return products need to deliver a consistent 95 – 98% control, whatever the time of year, whatever the climatic conditions. After crop GS30-32, in addition to the level of control, speed of control is essential to prevent cleavers smothering the crop and competing for light. Most damage to yield and profitability is done after this stage.
The longer the control of cleavers is left after GS32 the lower will be the return, despite the fact that cleavers can still be controlled successfully from applications of Starane 2 later in the season. Late emerging cleavers, i.e. those that appear around GS32, have less impact on final yield. They are more likely to be the source of seed return.
To maximise profitability from the control of cleavers applications should be made at or around crop GS32. Apply a cleavers herbicide with the T1 fungicide program. For products to deliver the required control at the appropriate time of the season they need to have certain key attributes.
Early Season Control – February to March
Must deliver consistent, high level of control of cleavers
Need to be able to control slow-growing cleavers and plants affected by autumn treatments
Must be able to work in a range of temperatures and weather conditions, especially cold and slow growing conditions
Speed of control is not important
Products based on active ingredients such as florasulam are most effective, namely Spitfire, Starane XL or GF-184.
Spitfire mixed with ALS graminicides at rates of 0.5 L – 0.6 L/ha will help bolster cleaver control early season.
Mid Season Control – April
Must deliver consistent, high level of control of cleavers
Need to be able to control slow-growing and fast-growing cleavers
Must be able to work in a range of temperatures and weather conditions, especially fluctuating diurnal conditions with high daytime temperatures and low night temperatures
Speed of control is important
Use products based on a combination of active ingredients, florasulam and fluroxypyr, to give rapid and consistent control under fluctuating conditions, such as Spitfire*, Starane XL, GF-184, Hiker*, Starane Gold or Starane Vantage.
Late Season Control – May onwards
Must deliver consistent, high level of control of cleavers
Need to be able to control fast-growing cleavers
Low and/or fluctuating temperatures are not normally an issue
Speed of control is essential
Products to control cleavers