A fungus detected for the first time in Costa Rica and Central America now puts strawberry crops at risk of losses up to 40 percent, researchers at the National University warned. The pathogen, Neopestalotiopsis rosae, causes crown rot and progressive wilt that can kill plants outright. Experts found it in strawberry plantations across Alajuela, Cartago and San José provinces.
José Calvo, coordinator of the Phytopathology Laboratory at the university’s School of Agricultural Sciences, described the signs. Plants develop yellow edges on leaves, circular spots, widespread tissue death, darkened crowns and steady wilting that ends in complete collapse.
Young fields already show the disease in close to 25 percent of plants. In the United States and Mexico, where the fungus appeared earlier, losses topped 40 percent in affected areas.
Calvo and colleague Abelardo Arroyo Vargas confirmed the identity with molecular tests. They amplified genes tef1 and tub2 from samples and matched them at 99.9 percent to reference sequences in GenBank. Phylogenetic analysis backed the result. They then infected healthy strawberry plants, reproduced the exact field symptoms and re-isolated the fungus, meeting Koch’s postulates.
The organism survives in plant debris and also lives as a saprophyte on decaying matter. It may adapt to other crops, including blueberries, mangoes and ornamental species. Strawberry farming in Costa Rica runs year-round on small highland operations that supply the local market. Producers had linked the symptoms to other issues before this identification.
No chemical products carry registration for control here. Calvo recommends biological strategies. Farmers can apply beneficial microorganisms such as Trichoderma fungi and bacteria from the Pseudomonas and Bacillus groups. These suppress the pathogen, support plant growth and strengthen soil microbiota. Removing crop residues after harvest also helps limit spread.
The university coordinates with the Agriculture Ministry’s Phytosanitary Service. Plans include training workshops for technicians and growers to manage the threat. Calvo stressed timely action. Early detection and prevention keep impacts low while proper handling protects production.
