Both old and young leaves from many parts of the field should be examined. Close examination of undersides of leaves, pulled at random, with a magnifying glass or hand lens is essential. Mites can be verified by the presence of red specks upon pressing leaves on a white background. Mites may be present all over the underside of the leaf or only in small colonies. Such colonies usually start in a hollow between leaf veins.
Mites spin very fine webs over the places where they are feeding.
Such webbing is easily visible when mites are abundant. In large numbers before casual symptoms can be recognzied without close examination of the plant. Badly infested leaves gradually lose their normal color and take on a yellowish or brownish cast. Such an appearance Is most often confused with plant diseases, nitrogen deficiency or dormancy of older leaves. Close examination revealing presence of mites or their webbing will establish the true cause of abnormal growth.