Poa annua

The Poa annua is one of the weeds  that we can find in the streets, roughsand even golf course greens. Germination is higher at a constant temperature of 16ºC than at 21ºC according to Cockerham and Whitworth (1967), while Bogart (1972) found no differences in germination at constant temperatures of 4ºC, 10ºC, 16ºC or 21ºC, although a large decrease was observed in the range of 27ºC to 32ºC. These studies, together with others by Hovin (1972); Engel (1967); Beard et al. (1978), confirm that poa germination occurs over a wide range of temperatures, with some reduction in very high or low temperature situations.

Poa greens can be found with very high standards, although they will be more difficult to manage than agrostis greens.

There are hundreds of biotypes of poa annua, so we can find in the same green different shades, which change according to the temperature.

The Poa can have 2 types of biology and life cycles:

1. Annual rate: Poa annua ssp. annuaIt has an annual life cycle, is easy to control and grows vertically. Its propagation system is sexual by seed. Greater seed production.

2. Perennial type: Poa annua spp.reptansIt has a life cycle that can exceed two years, being more difficult to control and its growth is lateral. Its propagation system is sexual and asexual (stolons). It produces fewer seeds.

Control of poa in agrostis greens can be achieved by using growth regulators such as paclobutrazol, where the population is small. This root absorption regulator requires subsequent irrigation application to eliminate unabsorbed traces, minimising toxicity. Three applications are recommended in autumn and another three in spring, applying a dose of 0.25 kg/Ha.

A preventative treatment for seed formation is given by the growth regulator Etephon (foliar uptake), which must be used mixed with Trinexipac ethyl (foliar uptake), taking into account the degree days.

The use of herbicides on agrostis greens is not common, as they are usually managed through these growth regulators.

However, nowadays herbicides such as Bispyribac-Sodium are available for use on agrostis greens, with the complementary effect of decreasing dollar spot, many of which have been shown to be effective in reducing the number of plants in the field. weeds and elimination of poa annua seed proliferation.

A new PoaCure product, Methiazolin from Asia also seems to be giving good results in eliminating poa. 

In contrast, on non-reseeded Bermuda greens and fairways, there are different alternatives including inhibitory ASL post-emergent herbicides such as trifloxysulfuron, foramsulfuron and rimsulfuron, which can lead to resistance. Pronamide (Kerb) is also an option.

Before considering the application of chemicals, professionals responsible for their use should review the specific regulations for the application of plant protection products, and any other regulations that may be applicable in each country.