What is ryegrass (Lolium multiflorum)?
Ryegrass (Lolium multiflorum) is a weed widely distributed in temperate regions of southern Brazil, as this species is cited as one of the few Poaceas (grasses) capable of full growth and development during the cold season of the year.
Ryegrass infests mainly wheat crops in addition to other winter crops such as oats, canola, barley, etc. On the other hand, for cattle breeders in the state of Rio Grande do Sul it is one of the main forage options for the winter period, being widely cultivated in the southern half of the state, mainly due to the quality of forage and adaptability in several regions.
In addition, in some regions of the state, ryegrass can still be used only as a cover plant during the winter period.
Features of ryegrass
The same characteristics that make ryegrass a good forage option to supply animal demand during the winter also guarantee it as a weed with a high competitive potential with winter crops, especially wheat. This is because it is an annual grass that has the potential to guarantee the natural reseeding of the species for the next year; excellent when we think about pasture, but a big headache for the wheat producer.
In addition to this characteristic, it has a highly branched and dense root system with large amounts of adventitious and fibrous roots. As for the stalks, they are cylindrical and erect, being able to become decumbent, and can reach about 100-120 cm with shiny leaf blades.
These characteristics, added to the presence of characteristic ligulas and auricles, can help in the differentiation of this species within the cultivation of oats, wheat and other winter cereals.
It is worth remembering that the first step in the control and management of ryegrass in winter cereals is the early identification of the species in the areas, together with effective management practices in the containment of the species.
What is the impact of ryegrass on wheat productivity?
The growth rate of ryegrass plants is superior to wheat plants and can considerably impact crop tillering, nutrient absorption, photosynthesis and the general aspects of wheat growth that will impact the final grain yield of the crop.
Studies indicate that only 1 ryegrass plant per square meter reduces the final wheat grain yield by 0.4%, and this percentage may be even higher depending on the wheat cultivar, soil, climate, among other factors. These observations reinforce the need for adopting efficient and early management practices.
Research indicates on average that between 10 and 30 days after the emergence of the crop, it is essential to keep the crop free from the presence of ryegrass, and it is recommended to prioritize ryegrass control from pre-planting desiccation to the end of the crop cycle, avoiding the establishment and production of infestation seeds in the area.
But how do I control ryegrass in wheat?
The chemical control of ryegrass after the establishment of the wheat crop is difficult due to the great morphological and physiological similarity between the species, therefore there are few herbicides selective for wheat and efficient in controlling ryegrass.
In this sense, it is important to follow the classic rule of “sow in the clean” and keep the culture in the “clean”. This rule means handling desiccation with products that are effective in controlling ryegrass and other weeds, as well as using residual (pre-emergent) herbicides to control new flows of ryegrass mainly in the early stages of the crop.
However, today there are few molecules registered and selective for wheat in the pre-emergent application modality and these herbicides in general demand high technical knowledge in their use.
It is also worth remembering the importance of keeping wheat free from invaders in the initial stages where the definition of the productive ceiling is being built.
Finally, after the emergence of the crop despite the wide range of herbicidal options for control, it is up to the producer to monitor the stage of the ryegrass plants so that the invasive control is carried out as early as possible, where most of the molecules available in market has a control spectrum restricted to the 3-4 leaf stages.
Conclusion
Ryegrass is undoubtedly the most important weed in wheat culture, due to its characteristics of growth and development, dispersion skills and potential to reduce productivity in wheat. Thus, the management of the invader is based on planning and identification of the species, involving the choice of suitable herbicides for pre-planting desiccation, the use of effective and selective pre-emergent herbicides for wheat and early post-emergence control in the stages. culture initials.
So stay tuned, the construction of high productivity in wheat has already started!
