Evaluation of Selected Biological and Chemical Treatments against Soil-Borne Diseases of Ginger in High Tunnel Production

Abstract

With its multifaceted health benefits, ginger is one of the commonly consumed dietary condiments with continued demand worldwide leading to more importation into countries such as the U.S. The rhizome of ginger, the seed-piece but also the edible portion, is highly vulnerable to pathogen infections causing seed-piece and soil-borne diseases (SSDs). Laboratory and high tunnel (HT) studies were conducted between 2018 and 2020 to evaluate the effect of soil and transplant drenches of selected biocontrol agents (BCAs) and chemicals. In vitro dual-culture tests revealed that the Trichoderma harzianum strain T-22 (Th-22) grew significantly faster than Fusarium oxysporum f.sp. zingiberi (Foz), the fungus causing yellows and rhizome rot in ginger. Th-22 grew more than three times faster than Foz within 3 days and engulfed the pathogen within 7 days when incubated at 30 °C. The bioproducts (RootShield® Plus, LifeGard®), an insecticide/nematicide (Vydate®) and disinfectant (10% Clorox) tested against Foz and any pre-existing pathogens in a HT significantly reduced severity of yellowing and rhizome rot when compared with the non-treated control. Yield was significantly higher for RootShield® Plus compared to the control in one of the trials. Spatially, declining ginger growth but an increased incidence of SSDs were observed as one walked from the door towards the back of the HT. Phospho-lipid fatty acid analysis showed better microbial activity on soils that received drenches of BCAs than on soils sampled pre-treatment.