Impact of <i>Aphelenchoides pseudobesseyi</i> on Soybean Growth and Yield in Colombia

In Colombia's Altillanura region, a soybean disease caused by the nematode <i>Aphelenchoides pseudobesseyi</i>, characterized by malformed leaves, thickened stem nodes, floral abortion, and reduced pod numbers, has led to significant yield losses. This study aimed to: (i) evaluate the damage caused by <i>A. pseudobesseyi</i> on soybean growth, and (ii) assess its impact on yield under semi-controlled conditions. A total of 238 soybean samples exhibiting characteristic disease symptoms were processed in the Nematology Laboratory at Universidad de Caldas, where <i>A. pseudobesseyi</i> was isolated and identified using morphological and molecular techniques. Two pathogenicity experiments were conducted with two treatments: inoculated plants (200 nematodes/plant) and non-inoculated control. Statistical analysis revealed significant differences (<i>P</i> < 0.05) between treatments. Six days post-inoculation, 100% of the leaf primordia in inoculated plants exhibited malformations, followed by blistering and central vein twisting by day eleven. At 45 days, average nematode populations reached 2,351 and 2,807 per plant in experiment one and two, respectively. Infected plants exhibited reductions in aerial dry weight by 28.4% and 24.7%, and seed dry weight by 50.3% and 53.2%, compared to controls. This is the first study in Colombia to quantify yield losses caused solely by <i>A. pseudobesseyi</i> in soybean plants under controlled conditions. Understanding the impact of <i>A. pseudobesseyi</i> on soybean growth and yield is essential for developing effective management strategies to mitigate its effects and improve soybean productivity.