What are the control methods for licorice rust?

        Damaged crop: licorice        Symptoms: mainly damages leaves. After the seedlings emerge in spring, round, grayish-white small blister spots appear on the underside of the leaves, and later the surface ruptures to reveal yellow-brown powdery masses, which are the pathogen's uredinia and urediniospores. In the late stage of the disease, the entire leaf blade of the whole plant is covered by uredinia, causing the aboveground part of the plant to die, and the phloem tissue at the junction of the stem base with the root or stem proliferates, latent buds sprout, and the plant shows clustering and dwarfing. After reinfection by urediniospores, dark brown telia are scattered on both sides of the leaves, and dark brown teleutospore powder is released. This disease is the main disease of cultivated licorice, occurring throughout all major licorice-producing areas, and is the main factor affecting dense planting.         Taxonomic attributes: Basidiomycota, Uromyces fungus         Distribution area: all major licorice-producing areas         Disease characteristics: The pathogen is a single-host parasitic rust fungus, overwintering as mycelium and teleutospores on the plant's roots, rhizomes and aboveground dead branches, and producing urediniospores the following spring. The incidence of the disease is higher in cultivated licorice than in wild licorice. If the previous autumn is rainy and the temperature rises relatively quickly the following spring, this favors its occurrence. In Yikezhao League, the peak period of urediniospore-infected plants of two-year-old cultivated licorice is in mid-May, with an infected plant rate of about 10%, and late June is the peak period of death of diseased plants, with a mortality rate of more than 90%. The peak period of teleutospore-infected plants is in mid-July.         Control methods: After harvest, thoroughly remove diseased plant residues from the field. Select uninfected, robustly growing plants for seed retention; irrigate in winter and spring, and cut off the aboveground stems and leaves at the appropriate time in autumn to reduce the occurrence of the disease. In the early spring, spray 20% triadimefon 1500-fold solution or 97% nabam 300-fold solution 2-3 times.         Commonly used agents: 20% triadimefon