Characterization and Control of Dendrobium officinale Bud Blight Disease

Abstract

Dendrobium officinale is an important traditional Chinese medicine (TCM). A disease causing bud blight in D. officinale appeared in 2021 in Yueqing city, Zhejiang Province, China. In this paper, 127 isolates were obtained from 61 plants. The isolates were grouped into 13 groups based on collected areas and morphological observations. Four loci (ITS, LSU, tub2 and rpb2) of 13 representative isolates were sequenced and the isolates were identified by constructing phylogenetic trees with the multi-locus sequence analysis (MLSA) method. We found the disease to be associated with three strains: Ectophoma multirostrata, Alternaria arborescens and Stagonosporopsis pogostemonis, with isolates frequencies of 71.6%, 21.3% and 7.1%, respectively. All three strains are pathogenic to D. officinale. A. arborescens and S. pogostemonis isolated from D. officinale were reported for the first time. Iprodione (50%), 33.5% oxine-copper and Meitian (containing 75 g/L pydiflumetofen and 125 g/L difenoconazole) were chosen to control the dominant pathogen E. multirostrata, with an EC50 value of 2.10, 1.78 and 0.09 mg/L, respectively. All three fungicides exhibited an effective inhibition of activities to the growth of the dominant pathogen E. multirostrata on potato dextrose agar (PDA) plates, with Meitian showing the strongest inhibitory effect. We further found that Meitian can effectively control D. officinale bud blight disease in pot trial.

Nigrospora oryzae Causing Leaf Spot Disease on Chrysanthemum × morifolium Ramat and Screening of Its Potential Antagonistic Bacteria

“…In order to verify the pathogenicity of the isolated fungi, according to Zhang’s method with small modification [ 18 ], the leaves and branches were put on a moist sterile filter paper in Petri dishes, a 7 × 7 mm mycelium plug was placed on the wounded leaves, and the sterile PDA was placed on the wounded leaves as the controls. The dishes were incubated in a growth chamber under artificial light (12/12 h light/dark) at 30 °C and 80% humidity, and the symptoms were observed after 5–7 days.…”

Assessment of the Dissipation Behaviors, Residues, and Dietary Risk of Oxine-Copper in Cucumber and Watermelon by UPLC–MS/MS

“…10,11 Oxine-copper, an organic copper fungicide widely used in agricultural production, was found to exhibit good protective and curative effects on angular leaf spot either as a single active ingredient or as a component of a mixture in the field. 12,13 It was effective against most bacterial diseases and some fungal and viral diseases. 14,15 After application, oxine-copper tended to evenly cover the plant surface and slowly release copper ions, which can effectively inhibit the germination and invasion of bacteria.…”

“…Oxine-copper, an organic copper fungicide widely used in agricultural production, was found to exhibit good protective and curative effects on angular leaf spot either as a single active ingredient or as a component of a mixture in the field. , It was effective against most bacterial diseases and some fungal and viral diseases. , After application, oxine-copper tended to evenly cover the plant surface and slowly release copper ions, which can effectively inhibit the germination and invasion of bacteria. , Oxine-copper is widely used in China on crops such as pears, apples, cucumbers, watermelons, and tomatoes . The dissipation of oxine-copper in citrus, apple, pear, loquat, bayberry, and river water has been studied, − and the results indicated that the degradation of oxine-copper by different crops was different.…”