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.
The saliva causes yellowing tomato plant leaves, and often makes the veins turn purplish. The stems of the plant will take on a zig-zag appearance. Once the saliva has taken over the tomato plant, it is difficult to save. For best results, dust the leaves with sulfur as soon as you notice symptoms.