How to control Kanzawa spider mite infestation in zinnia cultivation
Kanzawa spider mite (Tetranychus kanzawai) belongs to the class Arachnida, order Acariformes (Trombidiformes), family Tetranychidae, genus Tetranychus. It is mainly distributed in the eastern and central regions.
[Host plants] Zinnia, chrysanthemum, iris, snapdragon, rose, sweet pea, morning glory, cherry and other ornamental flowers and trees.
[Damage characteristics] It usually damages the underside of leaves, causing yellow spots on the affected leaves; when infestation is severe, the leaves turn brown and drop early.
[Morphological features]
The female mite is red, about 0.52 mm long and about 0.31 mm wide. The palpal terminal sensillum is columnar, and the dorsal sensillum is small and branch-like. The end of the tracheal groove curves in a U shape. The dorsal integumental striae of the posterior body form a diamond pattern.
The male mite is about 0.34 mm long and about 0.16 mm wide. The tip of the aedeagus curves toward the dorsal side, forming a terminal-outward hammer shape.
[Occurrence pattern] Several generations occur per year, and female mites overwinter on the underside of fallen leaves or remaining leaves. Female mites usually turn red before overwintering, then turn reddish-brown in body color the following spring and begin laying eggs. Reproduction is high between spring and summer. Under high temperature and dry conditions, one generation is completed in about 10 days. Generations overlap.
[Control measures] A. In winter, thoroughly remove infested leaves and fallen dead leaves to reduce overwintering sites and the next year's population. B. In the early stage of infestation, promptly spray 40% dicofol emulsifiable concentrate at 1000-1500 times dilution, or 50% tetradifon wettable powder at 1500-2000 times dilution, or 25% phosmet emulsifiable concentrate at 1000 times dilution for control. In winter, spraying 3-5 degrees Baume lime sulfur mixture can also be chosen to kill female mites overwintering on the underside of remaining leaves. When spraying, be sure to spray the underside of leaves.