Argentina (Tucumán): Studying an ecological control of nematodes in potatoes

"We are conducting research on the ecological management of Nacobbus aberrans in seed potato crops in Tafí del Valle, using an organic biological amendment with nematicidal properties (FFO)," said Juan Fernández, Daniel Ybarra, and Pablo Acosta, technicians from the Faculty of Agronomy and Animal Husbandry at the National University of Tucumán (UNT).

FFO is a consortium of microorganisms approved as an input for organic production in both Argentina and the European Economic Community, suitable for applications in rural, peri-urban, and even urban areas. "Among the microorganisms present in FFO are bacteria of the genus Bacillus sp, which make it effective and efficient for nematode control," they said.

Through foliar applications, the microorganisms present penetrate through the stomata of the leaves and are internally translocated through the intercellular spaces to all plant organs. “In potato crops, plant-parasitic nematodes, Nacobbus aberrans, are generally located in the growth zone of roots and tubers. Juvenile stages can be dispersed by soil movement, machinery, and irrigation water. Contaminated tubers contain egg masses and constitute the most efficient dispersal mechanism,” said Fernández, Ybarra, and Acosta. “The toxins injected by the nematodes into roots and tubers cause cellular hypertrophy and hyperplasia, which generates the typical galls. Galls cause reduction and alteration of the plant’s vascular system, resulting in chlorosis, wilting, reduced growth, and lower yield. The affected plants appear as patches, and the tubers lose quality,” they added.

A trial was conducted on seed potato crops in Tafí del Valle during November and December of last year, and during January, February, and March of this year, with the goal of controlling nematodes of the Nacobus genus, an endemic pest in the aforementioned area. To this end, FFO with nematicidal properties was applied to seed potato crops in different areas of the Tafí del Valle department: El Churqui, Santa Cruz, and Las Carreras.

Sampling

The trial began with soil sampling to determine the nematode species present and their population densities. Subsequently, FFO was applied at 50% to the seed potatoes before planting. When the plants reached 15 cm in height, a foliar application of FFO was made (10 liters of commercial product plus 1.5 kg of sugar in 100 liters of water per hectare). FFO applications then continued every 10 days (at the same dose) until 100 days into the crop, which coincided with the end of tuberization. At the end of the crop cycle, a second soil sample was taken to determine nematode population density and compare it with the initial situation.

In a potato field owned by Dante Oyola in Las Carreras, four applications of FFO were made over 100 days of cultivation. Weekly visual monitoring of the shoots and roots was conducted throughout the crop cycle, revealing uniformity of the plants in the field, as well as good root development and the absence of nematodes. Stems and leaves showed excellent growth and color, and tubers developed well.

In addition, yields increased by between 5,000 and 7,000 kilos per hectare on the plots of producers Ariel Nieva, Pascual Ibáñez, and Javier Moreno.