Study on the occurrence and Control of Cymbidium Diseases in Solar greenhouse

Guizhou is one of the main producing areas of orchid resources in China. There are 71 genera and 206 species of Orchidaceae in Guizhou Province, which are mainly distributed in the southwest and south. There are more than 180 species of Orchidaceae in Southwest Guizhou alone. Many Orchidaceae plants have important ornamental and medicinal value. However, due to indiscriminate mining and serious destruction of wild resources, there is an urgent need for excellent variety breeding and industrial production to meet the needs of the market and the protection of wild resources. However, in the transition from wild to artificial cultivation, due to the change of growth environment, the occurrence of diseases in large-scale cultivation is serious, especially retting heart disease, leaf spot and so on, which seriously affect the development and utilization of orchid resources. The occurrence of retting heart disease and leaf spot and the countermeasures of drug control of spring orchid in solar greenhouse were studied in order to provide scientific basis for local artificial cultivation and industrial production of orchid.

1 materials and methods

The tested varieties of orchids are Cymbidium goering-ii, and the varieties of pesticides tested are chlorothalonil: produced by Shanghai Zhongzheng Chemical Co., Ltd., 75% WP _ (10) 80g / bag. Boutique methyl thiophanate: produced by Shanghai Zhongxing Chemical Co., Ltd., FH70%WP,200 g / package. Dikesong: produced by Dandong Pesticide General Factory, Liaoning Province, 45% sodium disulfonate wet powder, 350g / pack; the tested substrate is lichen (Li-chenes).

1.2 the experiment scheme was carried out in the solar greenhouse, using pot field plot experiment, random block design, 50 pots per plot. According to the growth requirements of Cymbidium, water control is to spray water manually when water is needed. In the drug control experiment, seven treatments were set up: treatment A: spraying 800x solution of chlorothalonil; treatment B: 500x liquid of chlorothalonil; treatment C: 800x liquid of fine methyl topiramate; treatment D: 500fold liquid of fine methyl topiramate; treatment E: 500x liquid of dimethyloxone; treatment F: 400fold liquid of dimethyclovir; control (CK) did not spray. Each process is repeated 3 times, a total of 21 cells, random block arrangement.

1.3 Test items and methods the number of seedlings of retting heart disease: taking the death of heart leaves as the statistical standard, take the average value of 3 repeats. The number of leaves with leaf spot disease: the average value of 3 repeats was taken according to the susceptible death rate of 1 leaf. The number of seedlings per pot: the average value was counted by random sampling of 30 pots. The number of leaves per seedling: the average value was counted by random sampling of 30 seedlings.

1.4 the time and place of the test was carried out from May 1 to October 20, 2005 in the afternoon Tun Horticulture of Luyuan Animal and Plant Technology Development Co., Ltd., Qianxinan Prefecture.

2 results and analysis

2.1Leaf spot disease due to the percentage of diseased leaves in all treatments was less than 30% (i.e. PF0.01). Furthermore, the new compound range test between each treatment and the control showed that the difference between each treatment and the control reached a very significant level, in which the incidence of treatment D was the lowest (1.93%), followed by treatment A (2.1%), and the control treatment was the highest (8.45%). In addition, the differences between treatment D and treatment B, C, E and treatment F reached a very significant level, but the difference with treatment A did not reach a significant level.

2.2 the percentage of seedlings of retting heart disease in each treatment was analyzed by ANOVA. The results showed that there was no significant difference among the groups (Franch 0.750.05), but there was a very significant difference among the treatments (Franch 86.00 > F0.01). In order to further analyze the differences among different treatments, multiple comparisons of the new complex difference method were carried out, and the results are listed in the table. It can be seen from the table that the incidence of retting heart disease in treatment E, D and B is lower than that of the control, and the difference is very significant. Among them, the control effect of treatment B is the best, the incidence rate is only 0.49%, followed by treatment D is 0.59%. The incidence of treatment A, C and F was higher than that of the control, and there was a very significant difference between treatment A, treatment C and the control, but there was no significant difference between treatment F and the control.

3 summary and discussion

3.1 the cultivation results of Cymbidium in solar greenhouse showed that Cymbidium was infected with leaf spot and retting heart disease with different chemicals and different dosage treatments, and the average incidence was 3.61% and 0.93%, respectively.

3.2 the incidence of leaf spot in each treatment was significantly different from that of the control. In drug control, 500-fold solution of fine methyl topiramate was the best, followed by spraying 800-fold solution of chlorothalonil. The results showed that several drugs and their concentrations had good control effect on leaf spot disease and could control the occurrence of leaf spot disease to a certain extent. In the course of the experiment, the leaf spot rate of the control treatment cultivated in the shade greenhouse in the same period was 7.1%, while the infection rate in the solar greenhouse was 8.4%. However, among the treatments treated with drugs, the average infection rate in the solar greenhouse was 2.81%. The average rate in the shady shed was 3.22%, which indicated that the effect of drug control in the solar greenhouse was better than that in the shady greenhouse.

3.3 the incidence of retting heart disease of Chunlan cultivated in solar greenhouse was lower, and the effect of 500 times of chlorothalonil was the best in drug control. In the same period, the average incidence of spring orchid cultivated in shade shed was 2.99%, which was 3.2 times higher than that of spring orchid cultivated in solar greenhouse, indicating that the number of water spraying (rainfall) played an important role in promoting the occurrence of retting heart disease. The incidence of retting heart disease of Cymbidium without spraying treatment in solar greenhouse was 1.1%, and the average incidence rate of non-spraying treatment was 0.91%, while that of non-spraying treatment in shady greenhouse was 2.8%. The average incidence rate of each treatment treated with drugs was 3.02%, 3.3 times higher than that in solar greenhouse, indicating that the incidence of retting heart disease of cultivated Cymbidium in solar greenhouse was lower than that in shady greenhouse.