Symptom Identification and Control Methods for Leaf Spot Disease in Polygonatum
Polygonatum, also known as tiger ginger and chicken-head ginseng. It is the dried rhizome of Polygonatum kingianum, Polygonatum sibiricum, or Polygonatum cyrtonema of the Liliaceae family. Based on differences in the original plants and medicinal material characteristics, Polygonatum can be divided into three types: ginger-shaped Polygonatum, chicken-head Polygonatum, and large Polygonatum (also known as dish-shaped Polygonatum). The original plant of ginger-shaped Polygonatum is Polygonatum cyrtonema, the original plant of chicken-head Polygonatum is Polygonatum sibiricum, and the original plant of large Polygonatum (also known as dish-shaped Polygonatum) is Polygonatum kingianum. Among the three, ginger-shaped Polygonatum has the best quality.
Morphological Characteristics of Polygonatum
Polygonatum is a perennial herb with a horizontal, fleshy, pale yellow rhizome, sometimes with a protruding chicken-head-like tip at the apex. The stem is erect, 50-90 cm tall. Leaves are whorled, 4-6 per whorl, linear-lanceolate, 8-15 cm long, 0.4-1.6 cm wide, with curled tips. Flowers are axillary, usually in clusters of 2-4 small flowers, drooping, with a peduncle 1-2 cm long; the perianth is tubular, white to pale yellow, 0.9-1.2 cm long, with 6 shallow lobes at the apex; there are 6 stamens with relatively short filaments, 0.5-1 mm long; the style is 1.5-2 times the length of the ovary; the berry is spherical and turns black when mature. The flowering period is May-June, and the fruiting period is July-September.
The main characteristics of Polygonatum cyrtonema are: stem height 40-100 cm, leaves alternate, elliptic, ovate-lanceolate to oblong-lanceolate, with 3-5 veins. Pedicels bear 2-7 (-14) flowers, arranged in an umbel on the peduncle; the perianth is yellow-green, 1.8-2.5 cm long; the filaments have small papillae or fine hairs, enlarged at the apex into sac-like protrusions.
The main characteristics of Polygonatum kingianum are: stem height 1-3 m, the apex often twining, leaves whorled, 4-8 per whorl, linear to linear-lanceolate, 6-20 cm long, 0.3-3 cm wide, with acuminate and curling tips. Pedicels bear 2-3 flowers, not in umbels; the perianth is pink, 1.8-2.5 cm long; the berry is red when mature.
Symptoms and Control of Leaf Spot Disease in Polygonatum
What is leaf spot disease?
Leaf spot disease is one of the important diseases of melon, widely distributed and occurring in all regions, generally more severe in spring and autumn. The incidence rate is 10%-60%, reaching 100% in severely affected fields or greenhouses, and can reduce yield by 10%-30%, and by more than 60% in particularly severe cases. This disease can also harm cucumbers, winter melons, loofahs, bitter melons, and other vegetables.
Symptoms of Leaf Spot Disease in Polygonatum
Leaf spot disease in Polygonatum begins to occur in April-May. The affected leaves first show elliptical or irregular lesions at the leaf tip, with brown outer edges and pale white centers, spreading downward from the lesions, causing the leaves to wither and die. The disease is more severe during the rainy season.
Control Methods for Leaf Spot Disease in Polygonatum:
(1) After harvest, clean the field, gather and burn dead branches and diseased residues to eliminate overwintering pathogens.
(2) Before and in the early stages of the disease, spray 1:1:100 Bordeaux mixture, or 50% Tuzet 1000x solution, once every 7-10 days, for 3-4 consecutive sprays.