Control methods for rhododendron insect pests

The main pests of rhododendrons:

(1) Military insects: adult insects are small and flat, 3.5-4.0 mm long, and black. When the forewings are folded, they form an "X" pattern, and the wing surface is densely reticulated. The nymphs are dark brown with obvious spines. Adults and nymphs cluster in the host leaf dorsal and near the lateral veins of the feeding hazards. Yellow self-coloring spots appear on the surface of the infested leaves, and many black-brown insect droppings and (peeling) shells can be seen on the back of the leaves. Spray 50% ceivine wettable powder 500-700 times liquid; 50% octyl thion or 50% borer pine emulsion 1000-1500 times liquid control.

(2) Short whisker wax: mainly in the leaf back near the main vein of the sap sucking, July to September for the cattle vigorous period, often caused a large number of cuckoo leaves, seriously affecting fertility and ornamentation.

In addition, there are leaf bees, mesozoans and moths.

Physiological diseases: Rhododendron yellowing disease is a physiological disease, the main causes of the disease are as follows:

(1) Soil alkalinity: Rhododendron acidic soil. If planted in alkaline soil, the leaves of rhododendrons will turn yellow or even die.

(2) Soil iron deficiency: the iron element in the cultured soil is insufficient, and the chlorophyll synthesis is affected. The leaves become smaller and yellowish-white, especially in young leaves. The two are conjointed, and alkalinity often leads to iron deficiency.

(3) Improper maintenance: too strong or insufficient light, too much watering, excessive fertilization or insufficient, soil M weight, etc. Both can cause physiological disorders that can cause rhododendron growth to be poor. Yellowing and shedding of the leaves.

For yellowing disease, the above causes should be targeted and the right medicine should be prescribed. If yellowing is caused by iron deficiency, 0.2% aqueous ferrous sulfate solution can be sprayed or watered. Water every 7 days, 3-4 times continuously, the leaves will turn from yellow to green; For the yellowing caused by soil alkalinity, the soil should be acidified, and the acidic culture soil mainly based on saprophytic leaf spitting can be replaced; If yellowing is caused by improper maintenance, comprehensive conservation measures need to be taken.