Control of Landscape Nursery Stocks

I. Case Background

A certain urban square covers an area of 30,000 square meters and is a comprehensive public place integrating leisure, entertainment and cultural display. There is a rich variety of plants in the square, including tall trees such as Cinnamomum camphora and Osmanthus fragrans, shrubs like Rhododendron simsii and Ilex chinensis, as well as large areas of lawns and seasonal flowers. Recently, the problem of plant diseases and insect pests in the square has become increasingly serious. Through monitoring, it has been found that the main insect pests are spider mites and scale insects, and the main diseases are anthracnose and rust, which seriously affect the growth of plants and the landscape effect of the square, and pose a threat to the ecological balance. It is urgent to carry out pesticide control work.

II. Monitoring and Diagnosis of Diseases and Insect Pests

The greening management department of the square organizes professional technicians to adopt a combination of fixed-point monitoring and random inspections. Ten fixed monitoring points are set up in different areas of the square. Every week, a detailed inspection is carried out on the leaves, branches, roots and other parts of the plants. At the same time, personnel are arranged to conduct random inspections of the entire square every day. By observing the symptomatic manifestations of the plants and combining means such as microscopic examination and comparison of specimens of diseases and insect pests, it has been determined that a large number of spider mites have gathered on the backs of the leaves of some lawns and low shrubs, causing yellowish-white spots on the leaves, which turn yellow and fall off; scale insects are attached to the branches of tall trees and shrubs, sucking the sap and weakening the tree vigor; anthracnose forms circular or nearly circular lesions on the leaves of flowers and some shrubs, with a dark brown edge and a grayish-white center; rust causes rust-colored powdery spore piles to appear on the leaves and stems of plants. Information such as the occurrence area, damage degree and population quantity of diseases and insect pests is recorded in detail to provide a scientific basis for subsequent control.

III. Formulation of the Pesticide Control Plan

(I) Control Objectives

Effectively control the development of spider mites, scale insects, anthracnose and rust within 30 days, reduce the damage rate of diseases and insect pests to below 5%, restore the healthy growth of landscape plants, enhance the ornamental value of the square's landscape, and ensure the stability of the ecosystem.

(II) Pesticide Selection

1.For spider mites, abamectin·pyridaben emulsifiable concentrate is selected. This pesticide has contact and stomach poisoning effects, has a good control effect on all stages of spider mites, and is relatively friendly to the environment.

2.For controlling scale insects, buprofezin wettable powder is used. It can inhibit the growth and development of pests and interfere with their molting process, and is particularly effective against nymphs of scale insects.

3.For anthracnose, prochloraz-manganese complex wettable powder is chosen. It has the dual functions of systemic conduction and preventive protection, and can effectively inhibit the growth and spread of the pathogen.

4.For controlling rust, triadimefon emulsifiable concentrate is used. It can inhibit the synthesis of ergosterol in the pathogen, damage the cell membrane structure of the pathogen, and achieve the purpose of sterilization.

(III) Control Methods and Steps

1.Physical Auxiliary Measures: Before spraying pesticides, organize personnel to manually remove the diseased leaves and branches severely damaged by anthracnose and rust, and carry out harmless treatment in a centralized manner to reduce the source of the pathogen; for the branches with dense scale insects, gently brush off some scale insects with a soft brush to reduce the insect density.

2.Pesticide Spraying:
   Accurately prepare the pesticide solution at an appropriate concentration according to the instructions for use of the pesticides. Dilute the abamectin·pyridaben emulsifiable concentrate 1,500 to 2,000 times, the buprofezin wettable powder 1,000 to 1,500 times, the prochloraz-manganese complex wettable powder 800 to 1,000 times, and the triadimefon emulsifiable concentrate 1,000 to 1,200 times.
  Select to spray pesticides in the early morning (8-10 a.m.) or in the evening (4-6 p.m.) when there is no wind or a gentle breeze. Use a backpack sprayer to carefully spray low plants, ensuring that both the front and back sides of the leaves and the branches are evenly coated with the pesticide; for tall trees, use a vehicle-mounted sprayer for high-altitude spraying to ensure that all parts of the tree crown can be exposed to the pesticide solution. After the first spraying, carry out the second spraying at an interval of 7 to 10 days to consolidate the control effect.