Low-Level Copper Plus Chitosan Applications Provide Protection Against Late Blight of Potato

Fig. 3. A comparison of symptom development in potato plants (two plants/treatment) sprayed (25 ml/plant) with chitosan (25 µg/ml), CT-100 (14 µg/ml), CT-100 (14 µg/ml) plus chitosan (25 µg/ml), and the commercial fungicides copper hydroxide (600 µg/ml) and chlorothalonil (3.2 mg/ml). Sprayed leaves were excised and each of 49 leaflets per treatment inoculated with 25 µl of a 20,000-sporangia-per-ml suspension of P. infestans. Leaves were incubated 12 days at 16°C. Values of percent symptomatic leaflet area with the same letter are not significantly different based on LSD 0.05 = 10.66. Symptoms of the CT-100 only treatment included yellowing of the total leaf.



Image from Plant Health Progress article:
Low-Level Copper Plus Chitosan Applications Provide Protection Against Late Blight of Potato