The low chemical activity of the inert gases is due to the fact that their outermost, or valence, electron shell is complete, containing two electrons in the case of helium and eight in the remaining cases.
Often only one side of a plant is affected at first, but symptoms eventually spread. Tomato Leaf SpotâSeptoria lycopersici Fruit is not affected, although sunscald can be a problem due to foliage loss. Numerous brown spots on leaves, each about 1/16 inch in diameter. They do not have a yellow halo and they do have black specks in the center. First symptoms are usually on lower leaves after the first fruit sets.
f the leaves on your vegetable plants are. twisted or curled, the problem could be. environmental, chemical, or biological. Sometimes all the leaves on a plant are twisted. or curled; sometimes only new growth has. symptoms while older leaves are normal. Damage may start moderately then quickly. begin to affect new growth. Damage to tomato. and other vegetable plants may have one or a. combination of causes (Figs.