"Ziwei" Common Diseases and Pests and Their Control
If you want to learn about the relevant experience of the Ziwei flower clinic, the common diseases and pests of "Ziwei" and their control, the following article will introduce them.
Ziwei powdery mildew is a common disease on Ziwei plants, with some areas being more severely affected.
Symptoms: Ziwei powdery mildew occurs on young shoots, leaves, and flower buds. In spring and summer, infected young shoots and leaves become twisted and deformed, covered with a layer of white powder. The leaves can become infected after they open, with round spots covered with white powder. In severe cases, they can merge into one another. Diseased leaves may drop prematurely, affecting growth. Infected flowers become covered with a white powder layer, resulting in deformed flower spikes and losing their ornamental value.
Cause: It is caused by Uncinula austroliana Mcalp., belonging to the Pyrenomycetes, Erysiphales. It grows on both sides of the leaves.
Route of Infection: The powdery mildew fungus overwinters as mycelium in diseased residues and produces conidia the following year, which are spread by wind and rain, leading to infection. The disease usually starts in May, becomes severe in June, and stops or is less severe during hot weather in July and August. It can become severe again in September and October. Lower branches and leaves are more severely affected, especially in wet, cold, and poorly ventilated conditions.
Control Methods:
1. Horticultural control: Ziwei has strong germination, and heavy trees can be pruned of all the current year's branches in winter to remove diseased leaves and shoots, which can reduce infection. For potted Ziwei at home, diseased leaves should be removed promptly, and the potted plants should be placed in a well-ventilated and sunny area.
2. Chemical control: You can spray 80% Zineb wettable powder 500 times solution, or 70% Thiophanate-methyl 1000 times solution, or 20% Triadimefon 4000 times solution, or 1% Bordeaux mixture, starting from mid-May, spraying once every 10 days, for a total of 3-4 times.
Ziwei sootycrust disease
Symptoms: It primarily affects leaves and branches. The front of the leaves and branches, as well as petioles, are covered with a layer of black sooty powder, which affects photosynthesis. The powdery substance can sometimes be peeled off or washed away by heavy rain.
Cause: It belongs to the Deuteromycetes, Fungi imperfecti, sooty mold. The mycelium is dark brown, beaded, and lies on the leaf surface. Conidia are variable in shape, single-celled, double-celled, or brick-shaped. Conidiophores are erect, club-shaped, light brown, single-celled, 3-4 micrometers long, and 2-3 micrometers wide. There are also spherical conidiophores, with a diameter of 49-70 micrometers.
Route of Infection: The pathogen overwinters as mycelium on diseased leaves and branches. After the occurrence of large amounts of Ziwei woolly aphids and Ziwei long-spot aphids, their excreted sticky fluid serves as a nutrient source, causing the sooty mold to multiply rapidly. From late June to early September is the peak period of damage for Ziwei woolly aphids and Ziwei long-spot aphids, and high temperature and humidity favor the occurrence of this disease.
Control Methods: Prompt control of Ziwei woolly aphids and Ziwei long-spot aphids is the key factor in preventing sootycrust disease.
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