How to Identify and Control Soybean Rust? A Complete Guide to the Methods
Edamame is simply fresh soybeans in their pods; after being sun-dried, they are also called soybeans. The seeds are divided into six sizes by size: extra large: 100-seed weight above 30 grams; super large: 100-seed weight 24.1-30 grams; large: 100-seed weight 18.1-24 grams; medium: 100-seed weight 12.1-18 grams; small: 100-seed weight 6.1-12 grams; extra small: 100-seed weight below 6 grams. Edamame, also called vegetable soybean, is a soybean crop grown specifically for eating fresh tender pods as a vegetable. Edamame is simply fresh soybeans in their pods. Edamame is an annual crop with thick, hard stems covered in fine hairs; its pods are flat in shape and also covered in fine hairs, which is why people call it edamame (hairy bean). When fresh, the pods are tender green and delightfully verdant.
Basic Characteristics of Edamame
Edamame, commonly known as soybean or yellow bean, is the seed of the soybean plant in the Fabaceae (papilionaceous) family. It is an annual herbaceous crop, 30-90 cm tall, with thick, square-rhombic stems; the pods are rectangular, flat, 5-6 cm long, drooping, and densely covered with yellow slender stiff hairs; the seeds number 2-4 per pod, flat-elliptic to ovate when fresh, 0.8-1.5 cm long, light green, turning yellow, yellow-green, or purple-black when dry. Spring edamame, i.e. vegetable soybean, also called edamame, green edamame, or white edamame, refers to soybeans harvested at the green pod stage between full seed fill and early maturity; the pods are tender green and delightfully verdant. Once edamame matures fully, it becomes the soybean we are familiar with.
The biological classification of legumes is: Plantae, Spermatophyta, Dicotyledoneae, Rosales, an extremely broad category with about 690 genera and over 17,600 species. Edamame and soybean are both soybeans, belonging to the genus Glycine within the Fabaceae, classified under Eukaryota, Angiosperms, and Dicotyledons.
Identification and Control Methods for Edamame Rust
Symptom characteristics of edamame rust:
It mainly damages the leaves. Infected leaves are densely covered with small rust spots the size of pinheads, which are immature uredinia of the pathogen embedded beneath the host epidermis. As the uredinia develop, the epidermis ruptures and releases rust-colored powdery material (urediniospore masses). In the later stage, small black spots appear on the leaves, which are the telia of the pathogen, but these are only occasionally seen in southern Guangdong; edamame in Guangzhou and nearby areas generally produces only uredinia.
Pathogen and disease characteristics of edamame rust:
The pathogen is the soybean rust fungus [Phakopsora pachyrhizi Syd.], a fungus in the Basidiomycota. The pathogen primarily uses urediniospores as primary and secondary inoculum, spreading through wind and rain to complete the annual disease cycle. Warm, rainy, and humid weather or low-lying, damp planting site conditions favor disease development. A comprehensive survey of resistance differences among varieties is still lacking. Whether some varieties that generally show stronger disease resistance (as listed for edamame downy mildew) are also resistant to rust remains to be further investigated in various regions.
Control methods for edamame rust:
(1) Pay attention to finding and selecting resistant, high-yielding good varieties.
(2) Plant at a reasonable density, manage fertilizer and water well, and avoid excessive vegetative growth and overly wet soil to reduce disease incidence.
(3) Spray pesticides early for prevention and control. Combined with downy mildew control, starting when plants approach the row-closure stage, while spraying downy mildew control agents such as metalaxyl, add 25% triadimefon wettable powder at 2000x dilution, or 20% triadimefon-sulfur suspension concentrate at 1000-1500x dilution for simultaneous control. For fields where this disease is predominant, before symptoms appear, spray 40% carbendazim-sulfur suspension concentrate at 600x dilution, or ultrafine sulfur suspension concentrate or 29% lime sulfur aqueous solution at 200-300x dilution 1-2 times; after symptoms appear, switch to spraying the above-mentioned triadimefon wettable powder or triadimefon-sulfur suspension concentrate (same concentrations) 1-2 times.