Occurrence Patterns and Control Methods of Major Tea Plant Pests During the Summer Tea Season

Due to the low-temperature rain and snow weather last winter and this spring, the overwintering generation of tea pests this year had a low population base and a delayed occurrence period, and damage during the spring tea season was relatively light. However, summer weather is more suitable for the occurrence and damage of pests and diseases, so monitoring and control work must be carried out effectively.

Camellia spiny whitefly (Aleurocanthus spiniferus): The occurrence level was lighter than last year, but pest numbers in some tea gardens still exceeded the control threshold. According to a survey by the Songyang County Plant Protection Station: the peak period of overwintering adults was April 15, with an average of 17.4 insects per 100 leaves, later and fewer than last year (April 5). The hatching peak of the first generation of camellia spiny whitefly this year is predicted to be around May 15. The appropriate control period is May 15 to 25. In northern Zhejiang, the appropriate control period is delayed by 3-4 days. All localities should strengthen field surveys and seize the appropriate control period. Low-volume side-position spraying can be used, and the spray must reach the undersides of old and mature leaves. For pesticides, 10% imidacloprid 20-30 g/mu or 40% chlorpyrifos 50 mL/mu can be selected, and the spray volume per mu should be more than 30 kg.

Tea geometrid (Ectropis obliqua)

The first-generation population of tea geometrid was similar to last year. During the spring tea season, because no chemical control was carried out, more insects remained in the field. The second generation of tea geometrid is expected to occur at a moderate to severe level, and some tea gardens may experience heavier occurrence. According to an age-specific field survey of first-generation larvae conducted on April 16 in tea gardens in Longwu Town, Xihu District, the second instar was dominant. The peak period of second-instar larvae of the second-generation tea geometrid is predicted to be around May 27. In northwestern Zhejiang tea areas, it is delayed by about 2-3 days, while in southern Zhejiang tea areas it may be 3-4 days earlier. All localities should begin field surveys at the end of May to determine the area for chemical control. Tea gardens with more than 4,500 insects per mu should all be sprayed for control. For pesticides, 2.5% deltamethrin 20-25 mL/mu or 5% natural pyrethrum emulsifiable concentrate 80 mL/mu can be selected. Organic tea gardens may use tea geometrid nuclear polyhedrosis virus preparations.

Tea tussock moth (Dasychira baibarana)

The second generation of tea tussock moth is the main damaging generation of this pest. According to an age-specific field survey by the Hangzhou Tea Research Institute, based on the developmental duration method, the peak period of second- and third-instar larvae of the second-generation tea tussock moth is predicted to be around June 12, and the appropriate field control period is June 13-18. Tea gardens with more than 3,700 insects per mu should be fully sprayed for control. For pesticides, 2.5% bifenthrin 25 mL/mu, or 80% dichlorvos 150 mL/mu, or 2.5% bifenthrin 15 mL/mu + 80% dichlorvos 50 mL/mu can be selected.

occurrence, with relatively high pest numbers in some areas. Based on an analysis of the average temperature in January and February and the rainfall in March and April this year, the first field appearance of adults of this pest this year is predicted to be around May 14, similar to last year, and the appropriate field control period is May 28 to June 3. All localities should strengthen field surveys around May 25 and carry out chemical control in tea gardens with more than 8,000 insects per mu. For pesticides, 98% cartap 60 g/mu or 2.5% bifenthrin 60 mL/mu can be selected, and low-volume sweeping spray over the canopy is suitable as the application method.

Smaller green leafhopper (Empoasca onukii)

The first peak damage of the smaller green leafhopper is expected to occur at a moderate to severe level. Based on the average temperature in March and April this year, the peak period of this pest will be before May 20, making it an early-occurrence year. All localities should begin field surveys on May 15, and tea gardens with more than 8 insects per 100 leaves should all be fully sprayed for control. The appropriate control period is when nymphs account for more than 80% of the total pest population. For pesticides, 2.5% bifenthrin 25 mL/mu, or 10% imidacloprid 15-20 g/mu, or 98% cartap 25 g/mu can be selected. Organic tea gardens may use Beauveria bassiana preparations and matrine preparations.

(Note: The pre-harvest intervals for the above pesticides are: bifenthrin 6 days, dichlorvos 6 days, deltamethrin 5 days, imidacloprid 10 days, chlorpyrifos 10 days, cartap 7 days. For tea gardens at export bases, the pesticide varieties selected must be determined according to the pesticide residue requirements of the exporting country.)