An Evaluation of Humates On Disease Resistance of Field Tomatoes to Early Blight

Previous studies have shown that humates enhance the plant’s natural defense against disease and toxins.  A field study evaluated the effect of humate (LC-12 Organic Approach) on ‘Mt. Fresh’ tomato (Lycopersicon esculentum) resistance to early blight.  A preliminary greenhouse screening indicated that ‘Mt. Fresh’ was responsive to humate treatments.  Three levels of humates were used (94, 471, 940 ppm) with controls receiving water.  The trial was arranged in a randomized block design with four replications of each treatment.  Eighty days after planting, leaf tissue was randomly selected from each of the replications for nutrient analyses and chlorophyll content.  Designated sectons of the field were inoculated with mycelial and spore suspensions of Alternaria solani.  Starting eight days later, tomato fruits were harvested and data on total yields, percentage of diseased fruit, fruit weight, and fruit circumference were compared and analyzed statistically.  It was found that nutritional analyses showed no consistent differences between humate treatment groups and controls.  There was no correlation between mean leaf chlorophyll and nitrogen in any treatments.  The trial also revealed that the control treatment (no humate) performed as well or better than humate-treated plants as far as total harvest, total weight, mean circumference, marketable fruit, and percentage of diseased fruit.  Therefore, the tomato field trials revealed overall that the control treatment (no humate) performed as well or better than the treatments with humate.