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Fig. 1. Illustration of the visual rating scale used to establish the Damage Index (DI). 0 = No aphids, plant appears normal and healthy; 1 = Less than 100 aphids per plant, plant appears normal and healthy; 2 = 101–300 aphids per plant, mostly on the young leaves and the tender stem at top of plant, plant appears normal and healthy; 3 = 301–800 aphids per plant, leaves slightly curly and shiny, young leaves and stems covered with aphids; 4 = More than 800 aphids per plant, plants stunted, leaves severely curled, yellow, covered with sooty mold and cast skins.
