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.
Remove the Bottom Leaves. Once your tomato plants reach about 3 ft. tall, remove the leaves from the bottom 1 ft. of stem. These are the oldest leaves and they are usually the first leaves to develop fungus problems. As the plants fill out, the bottom leaves get the least amount of sun and air circulation.. Once your tomato plants reach about 3 ft. tall, remove the leaves from the bottom 1 ft. of stem. These are the oldest leaves and they are usually the first leaves to develop fungus problems.