Detailed Explanation of the Damage Symptoms and Control Methods of Rose Stem Sawfly

Many flower lovers are very familiar with the rose leafcutter bee, but the rose stem sawfly is probably unfamiliar. In this article, we will first learn about the knowledge related to the rose stem sawfly, then study how to control it, striving to let flower lovers see useful information.

Rose stem sawfly: also called rose stem sawfly, rose stem borer, rose heart borer, etc. Besides damaging roses, it also harms Rosa multiflora, roses, Rosa xanthina, etc. Its main mode of damage is through the larvae, which bore and feed in the pith of the stem, destroying the vascular tissue of the stem and blocking water and nutrients.

Specific manifestations of stem sawfly damage: causing branches to break, wilt, and die, increased sprouting at the base, and new shoots turning black and drooping.

Control of rose stem sawfly: When rose stem sawfly is found, the damaged branches should be cut off at any time (cut until there is no boring tunnel in the stem pith) and destroyed. In addition, when we prune in winter, we must cut off any branches found to contain insects. If the insect body is found to have entered the root, a syringe can be used to inject 5-10ml of 50-fold diluted 6% imidacloprid emulsifiable concentrate into the hole, and it should be immediately sealed with mud.

For ordinary flower lovers, in addition to dealing with branches, it is best to appropriately consider some insect-resistant varieties when choosing varieties.

Control Methods for Potted Rose Pests and Diseases

Rose black spot: The pathogen mainly infects the leaves, and also harms petioles, young branches, pedicels, and petals. In the early stage of the disease, black spots appear on the leaves, gradually expanding into purplish-brown lesions with radiating edges. Many small black granular spots are scattered on the lesions. In the later stage, the lesions connect, and the leaves turn yellow and fall off. This pathogen is a fungus and overwinters on diseased plant residues as mycelium or acervuli. In the Beijing area, scattered occurrences appear in mid-May, the initial disease period begins in early to mid-June, the peak disease period is reached in mid-August, and the disease declines in September. The lower old leaves fall off early, easily forming bare legs. You need to: fertilize reasonably, pay attention to irrigation methods, prune moderately, improve ventilation and light transmission, and enhance disease resistance; promptly clean up diseased branches and leaves to reduce sources of infection; in the early stage of the disease, spray 75% chlorothalonil wettable powder at 800 to 1000 times dilution, or 400 times dilution of myclobutanil, once every 10 to 15 days, continuously spraying 5 to 6 times, which can control the occurrence of the disease; choose disease-resistant varieties, such as rose 'Strawberry Ice Cream', 'Matilda', 'Queen', 'Mannheim', etc.

Rose powdery mildew: It mainly occurs on leaves, and in severe cases spreads to young branches and flower buds. In the early stage, the lesions are chlorotic yellow spots, and young leaves shrink, curl, or become deformed. In severe cases, the entire leaf is covered with a layer of white powder, the leaves twist and curl backward, the young shoots bend, the buds do not grow, the flower buds wither, and the flowers cannot open normally. Its pathogen is a fungus, which overwinters as mycelium on diseased buds, diseased branches, and diseased leaves of the host plant. In the following spring, it produces conidia, spreads through wind and rain, and directly infects. In Beijing, the disease is severe from May to June and from September to October. In early summer, continuous rain is not conducive to the disease, while high temperature and high humidity after rain are conducive to the occurrence of the disease. In addition, applying too much nitrogen fertilizer also makes the disease more likely.

You need to: strengthen cultivation management and improve plant disease resistance, such as increasing phosphorus and potassium fertilizer and improving ventilation and light transmission; promptly clean up diseased branches and fallen leaves to reduce sources of infection; using 100 to 150 times dilution of agricultural antibiotic 120 or antibiotic B010 emulsion has a good control effect. In the early stage of the disease, use domestic 75% plus trimorpholine emulsion at 1000 times dilution or Antaisheng at 700 times dilution for control.

Rose Pests and Diseases - Nematodes, How to Remove Them?

Roses mainly have landscaping, environmental protection value, medicinal value, and ornamental value, and the flowering period is very long, so how do nematode pests reproduce in roses?

Nematodes mainly harm the roots of flowers. When nematodes occur, the plant's leaves turn yellow, the leaves become smaller, and the plant lacks vitality. The quality of cut flowers is low. When pulled up for inspection, root knots of varying sizes can be seen, initially yellow-white, smooth and firm, later turning yellow-brown. The root system of diseased plants is weak and sparse, and may even rot, hindering growth. There are more than 10 species of nematodes that harm roses.

In China's cut rose production, there is still insufficient awareness of the harm caused by nematodes. Plants during the production period should be regularly dug up and inspected, especially in areas with poor growth, where whether there is nematode damage should be considered even more.

Methods for controlling rose nematodes:

1. First, start with the seedlings. The rootstock should be soaked in 1000 times dilution of 45% methomyl for 30 minutes, and the land used for planting seedlings should adopt crop rotation;

2. The soil must be disinfected before greenhouse renewal and replanting;

3. Drugs for killing nematodes include aldicarb, cadusafos, etc.

The above are the symptoms and control methods of rose nematode pests.