Nematode Control Measures for Flowering Pot Plants and Bonsai and Key Points for Seed Preparation Before Sowing

At the request of some floriculture and horticulture departments, we need to put forward treatment opinions on pest control issues for the garden pot plants and bonsai under their jurisdiction. To this end, we made a special trip to the base to learn about the growth and management of bonsai and flowers, and listened to introductions on the current occurrence of nematodes and other pests. The relevant treatment plan is proposed as follows:

I. Main problems existing in flowering pot plants and bonsai

At present, woody plants in bonsai carry nematodes, which directly affects the export market. Although some traditional practices have been adopted and relatively good control results have been achieved, the roots of some flowering pot plants and bonsai have already been affected, causing exported flowering pot plants and bonsai to wilt, shed leaves, and even die. After comprehensive analysis, this is caused by the following reasons.

1. Main control methods currently adopted

At present, woody seedlings for export must be treated with pesticides before repotting and export, so that potted bonsai absorb the pesticide solution before export, or are repotted and held for a period before export. We believe that this nematode control method is a current traditional approach and can be used when plants are placed at high density in greenhouses. However, it also brings the following problems.

(1) The pesticide is used for too long a time, and phytotoxicity directly affects root growth. It has been reported that seedling roots turn black; this is the main reason phytotoxicity affects seedling growth.

(2) No comparative trials have been carried out according to the age and species of flowering pot plants and bonsai. The same method is used regardless of tree species or age, which causes phytotoxicity in species with poor pesticide tolerance.

(3) No trials have been conducted on multiple pesticide varieties. Besides some pesticide varieties that can be used, some have already been registered and some have not been registered, and there are risks in use regarding efficacy, residues, and phytotoxicity.

2. Suggestions for improvement

(1) Nematodes are mainly spread through soil. Therefore, using nematode-free soil is the key measure. It is therefore suggested that the current soil treatment methods be further improved in terms of cost and effect.

(2) Increasing the concentration of the pesticide solution and mixing it with other pesticides will affect root growth.

(3) When nematode treatment pesticides are already in use, other pesticides should not be used blindly.

(4) While reducing pesticide concentration, comparative trials should also be carried out on bonsai of different ages and different varieties, so as to screen out different application frequencies for different ages and varieties.

(5) Seek new pesticides to treat nematodes. It is suggested that trials be carried out with different pesticides at different concentrations, on different varieties, different ages, and at different times, in order to determine whether they can replace existing pesticides for nematode control.

II. Several suggestions for strengthening pest control

1. Experts should determine as soon as possible comprehensive observation and technical guidance for the prevention and control of pests and diseases in various types of bonsai, rather than relying entirely on self-exploration. Do the current work well and build up technical reserves to guard against the impact of "green barriers."

2. Add necessary instruments, equipment, and an observation room. Add necessary instruments at the base so that control can be carried out while effects are observed.

3. Collect information from both domestic and international sources on bonsai cultivation, varieties, and pest and disease control, so as to improve the survival rate and growth speed of bonsai.