In Mar del Plata, Rizobacter launched its technological portfolio for this campaign. During the event, Dr Marcelo Carmona, Phytopathology professor at FAUBA, explained the importance of including health in the quality parameters of the soybean seed, and more efficient mechanisms of control.
Within an issue which proposes to rethink this ‘turnkey contract’ agricultural model, the engineer Marcelo Carmona spoke at Rizobacter’s presentation of the gross campaign 2016-2017 in front of distributors, technicians and farmers. “Today, investing in biotechnology is not enough, it is necessary to invest in knowledge per hectare”, maintains the specialist, defending a more complex approach which integrates multiple variables, analysis criteria and technological approaches.
In a year in which seed quality is at the heart of the picture, there are certain variables that will inevitably generate more efficient and sustainable production strategies.
The first topic deals with how we define and act in relation to the, “Quality of the seed”. Undoubtedly, all the historically known parameters come together here (mainly, germination power and vigor). However, under the current conditions, it is equally important to include health as a highly significant point; that is, to know that pathogens are present in the seed and their percentage of infection.
Moreover, there are a lot of seeds that don’t show external symptoms, but nevertheless are infected. Therefore, although seed analysis is a practice which farmers should have already incorporated, in this campaign not only is it an obligation but it is also recommended to be carried out before and after the treatment and more than once a year.
In addition, it is as important to analyze the plot and the date on which planting is to be carried out. “Above all because, as is known, there have never been so many consecutive years with cloudy and rainy days damaging the pod and, consequently, the seed. We have 80% of the soybean seed with problematic quality (and 4 million lost tons), which are the ones harvested after bad weather. Alterations in the color, size and shape can be observed, as well as a reduction in the GP and a significant increase in fungus, pathogens and saprophytes. Most of them only reach a GP of 40-50%, but after curing”, explains Carmona.
The main problem of planting an infected seed is the death of the seedlings and the introduction of fungus, bacteria and viruses into the crop area. Through the infected seeds, pathogens are introduced into new areas, survive in the absence of cultivated hosts, are disseminated as new more virulent species and are distributed as primary focuses of infection.
“Generally, seed control is more difficult in legumes than in the case of wheat or corn, because they have an interesting botanical and physiological peculiarity which allows them to strip the seed coat in order to take out the cotyledons, also leaving aside the part of the fungicide present in the seed coat. This is why it is good to observe the cotyledons at the emergence stage because many times it ‘discarded’ the bad or the good treatment”, deepened the specialist.
In addition, unlike wheat, the damage caused by soil pathogens is key because it can ruin the crop. Accordingly, it is essential to think hard about the molecule being chosen for both paths, the seed and the soil. And in a year like this we have to think even more.
Which are the best control strategies?
As regards seeds, the most efficient control strategies are associated with having healthy seeds, with germination and vigor parameters within what’s recommended, without mechanical damage and with the incorporation of the correct treatment. If you have poor quality seeds, it is advisable not to plant in the early stages, because the risk is higher.
For a good chemical treatment, three steps must be followed: First, carry out a seed health assessment; Second, register the epidemics from the last campaign of the plot to be planted; And third, know the active ingredients to be used, their dosage and combinations.
The main idea is to choose the most fungitoxic molecules for the sensitivity of the fungi necessary to be controlled. A single molecule is not advisable, since it has been proven that mixtures help to combat the resistance mechanisms of fungi to fungicides, because they operate on different levels and via different mechanisms of action.
As regards control strategies on fungal or soil diseases, the following issues stand out: Avoid waterlogged soils, plant in indicated seasons, avoid early plantings, carry out crop rotation, pay attention to the best nutrients and suppressiveness, improve the physicochemical properties of the soil, avoid deep plantings so as not to give so many opportunities for fungi to develop and avoid soybean plantings in plots with previous records of Fusarium in corn or wheat.