Pesticides on the viability of Pochonia chlamydosporia for controlling Meloidogyne incognita

One of the major challenges for biological control candidates is the ability to survive after contact with chemical pesticides, which are regularly used in the conventional agriculture. The use of a biological tool does not eliminate the need for less sustainable practices to protect the crops in the field. Therefore, this study evaluated the compatibility of the fungus Pochonia chlamydosporia with pesticides commonly used in cotton and soybean crops. The tests were performed in vitro and in the greenhouse. For the in vitro test, the isolate Pc - 10 of P. chlamydosporia was transferred to Petri dishes containing potato-dextrose-agar medium and agricultural pesticides in different concentrations. The evaluations of the growth were performed by measuring the diameter (cm) of the colonies. To evaluate the compatibility of P. chlamydosporia with the pesticides in soil, a greenhouse experiment was conducted with cotton and soybean seeds treated with a combination of the fungus and each pesticide separately. Seeds treated only with P. chlamydosporia were also prepared. Each pot soil was infested with 3000 eggs of Meloidogyne incognita race 3 for cotton, and 3000 eggs of M. incognita race 2 for soybean. Each pot received one seed of cotton or soybean pretreated with one pesticide and P. chlamydosporia. For the positive control treatment, each seed was only treated with P. chlamydosporia. A non-treated seed per pot was used in the negative control. In the in vitro tests, the fungus P. chlamydosporia was sensitive to all agrochemicals used. However, in the greenhouse experiments, the fungus could survive, colonize the roots and the soil, and consequently reduces the M. incognita populations. This study demonstrates the feasibility of the combined use of fungicides, insecticides and nematicides with P. chlamydosporia without compromising the activity of the biological agent.