The volume of flame, however, is increased by inert gas, and there is a proportionate diminution of the heating effect. Encyclopaedia Britannica, 11th Edition, Volume 11, Slice 3 Various. Nitrogen by itself is an inert gas, colorless and uninflammable. Scientific American Supplement No. 819 Various.
Tomato Spotted Wilt Virus. The tomato spotted wilt virus (TSWV) causes dark brown, purple or black spots on leaves. The spots can spread to the stems, causing cankers and streaks. The foliage begins to wilt once the disease spreads, and the leaves become stiff.
Early blight shows up as a leaf blight on the lower part of plants. The disease moves upward, and by early to mid-summer, early blight has caused a firing-up of foliage over most of the tomato plants in the garden. As the disease progresses, leaves turn yellow, wither, and drop from plants.