Control of Edible Fungus Diseases and Major Fungal Diseases of Zingiberaceae Flowers

1. Brown spot

This disease is seen on the leaves of Amomum villosum var. xanthioides, Alpinia oxyphylla, and Hedychium coronarium. The spots on the leaves are nearly round, irregular, or elongated, brown or grayish brown, with dark brown edges. The spots often begin at the leaf tip or leaf margin, and bear many small black dots. It is prone to occur where shade is insufficient and management is neglected.

Control method: Spray with thiophanate-methyl at 1000 times dilution for control.

2. Anthracnose

It damages the stems and leaves of Hedychium flavum, Amomum villosum, and Alpinia galanga, mostly occurring on mature plants. The spots mostly begin at the leaf tip or leaf margin, initially as dark green water-soaked small dots, then turning grayish white, and later grayish brown, appearing cloud-patterned, with dark brown edges and a withered white center. When humidity is high, many small black dots appear on the spots. This disease mostly occurs in autumn and winter. It is more severe in plots with poor soil, insufficient base fertilizer, excessive quick-acting nitrogen, and poor shade. Rainy and high-humidity conditions favor the occurrence and spread of the disease.

Control method: Spray with 50% carbendazim wettable powder at 500 times dilution, 65% zineb at 600-800 times dilution, or 75% chlorothalonil at 800 times dilution for control.

3. Leaf spot

This disease occurs on Hedychium gardnerianum, Alpinia zerumbet var. variegata, Costus speciosus, Amomum villosum, etc. It mainly occurs on leaves and can also damage leaf sheaths. On Amomum villosum, at the early stage of the disease there are chlorotic small dots, which gradually expand into round or irregular water-soaked spots with indistinct edges; while on the diseased leaves of Costus speciosus, the leaf spots are irregular, grayish green in the center, with an obvious brown necrotic line at the edge, and when humidity is high, a grayish green mold layer grows in the center of the spots; on Alpinia zerumbet var. variegata, the affected leaves show elliptical or long elliptical spots, brown, gradually expanding into irregular shapes, with a pale grayish brown or brown center, brown edges, concentric rings, and numerous black dots on the surface. This disease can occur year-round, with two peaks in September to October and the following March. During the peak periods of the disease, a large number of leaves can wither. It is severe in planting sites with poor management, poor ventilation, overly dense planting, waterlogging, poor soil, insufficient shade, and poor plant vigor. Diseased plant residues are the source of primary infection for this disease.

Control method: At the time of disease occurrence, spray with 75% chlorothalonil wettable powder at 1000 times dilution plus 70% thiophanate-methyl wettable powder at 1000 times dilution, or 50% procymidone wettable powder at 2000 times dilution for control, once every 7-10 days, for 2-3 consecutive times.

4. Gray spot

This disease occurs on some hosts such as Alpinia, Amomum, Costus, and Zingiber, as well as intergeneric hybrids of the first two genera. The affected leaves begin from the leaf tip or leaf margin, or produce irregular round spots in other parts. The center of the spots is grayish white or grayish brown, and the edges are brown or dark brown. Most spots have concentric rings. The spots on Alpinia katsumadai also have water-soaked necrotic lines at the edges; while the spots on Alpinia speciosa have a yellow band at the junction with healthy tissue. This disease is generally seen in winter and spring and causes relatively mild damage.

Control method: Spray with 50% carbendazim or thiophanate wettable powder at 800 times dilution for control.

5. Spot blight

This disease occurs commonly on plants of Alpinia, Amomum, Costus, and Hedychium, and is especially severe on Hedychium coronarium and Hedychium flavum. The spots on the leaves often begin at the leaf tip or leaf margin, or extend downward from the leaf tip along the leaf margin. The spots expand relatively quickly. Spots not at the leaf tip or leaf margin are nearly round or round, and small black dots grow in the center of the spots. This disease mainly occurs in plots with insufficient shade and neglected management, and can be seen year-round.

Control method: Remove diseased leaves and spray with Bordeaux mixture at 200 times dilution.

6. Speckle disease

It mainly damages the leaves of ginger, etc. The disease often develops rapidly, quickly causing the entire leaf to wither and die. At the early stage on affected leaves, the spots are yellow, elliptical or nearly round, with the center gradually turning grayish white and the edges brown, with a yellow halo outside the spot. Small black grains are scattered on the grayish white part of the spots, and longitudinal cracking often appears on the spots. This disease can occur year-round, with peaks in summer and autumn. It is severe in plots with poor management and severely insufficient shade.

Control method: At the early stage of disease, promptly remove diseased leaves and spray with 75% chlorothalonil wettable powder at 600 times dilution, or 50% iprodione wettable powder at 1500 times dilution, 40% captan wettable powder at 400 times dilution, or 70% fosetyl-aluminum · mancozeb wettable powder at 500 times dilution, or 50% thiophanate-methyl wettable powder at 500 times dilution for control, once every about 10 days, for 2-3 consecutive sprays.

7. Leaf blight

It causes relatively severe damage on Hedychium gardnerianum, Hedychium coronarium, Alpinia zerumbet var. variegata, etc. When Hedychium coronarium is affected, the leaf tips begin to yellow, growth stagnates, and finally they wither.

Control method: At the early stage of this disease, spray with Bordeaux mixture at 200 times dilution or 65% zineb wettable powder at 600 times dilution every 7-10 days for control.

8. Southern blight

This disease occurs from time to time in the cultivation of Alpinia zerumbet var. variegata, Hedychium coronarium, etc. When it occurs, the stem or leaf base near the soil turns brown and rots, and white silky mycelium grows, radiating outward, capable of spreading in the rhizosphere soil, and then causing the aboveground parts to wither and die. It is relatively severe in July to August, and is prone to occur when the soil is too wet, poor, and lacking fertilizer.

Control method: Add 70% quintozene at 0.2% of the soil weight to the soil to disinfect it. During cultivation, pay attention to ventilation and prevent overly dense planting.

9. Rust

It occurs in a small number of Hedychium plants, damaging leaves, etc. When it damages plants, small yellow spots first appear on the lower leaf surface, then bulge into grayish white pustule-like structures, and then turn brown. In severe cases, the entire leaf is covered with disease spots, causing the plant to wither and die early.

Control method: Spray with 20% triforine emulsifiable concentrate at 1000 times dilution or 20% triadimefon emulsifiable concentrate at 2000 times dilution for control.