Disease and Pest Control of Small-fruited Rose

1. Powdery mildew

1. Symptoms

The disease often occurs on leaves (including leaf blades and leaf stalks), flower buds and tender young shoots.

(1) Leaf disease: White powdery mildew spots appear on the leaves. The disease usually starts from the tip or edge of the leaf and spreads to the inside in a brown color, causing the entire leaf to dry up and fall off.

(2) Young shoots: The chlorosis phenomenon gradually expands the scope of infection, with white powdery spots appearing on both the front and back sides. After spreading to the entire leaf, the leaves turn light gray or dark red, causing the leaves to deform and shrink.

(3) Flower buds: The white powdery bacteria will cover the flower buds and pedicels, causing the flower buds to be deformed. Timely treatment is required. In severe cases, the plant will die.

2. Solution

(1) To prevent it, you need to ventilate more, provide a good drainage environment, and reduce moisture;

(2) Once diseased strips or leaves are found, the diseased parts should be cut off in time during winter pruning to prevent the spread of the disease.

(3) During the disease period, attention should be paid to fertilization. Phosphorus fertilizer and potassium fertilizer can enhance the plant's ability to resist pathogens, and nitrogen fertilizer should be applied less.

(4) In the early stage of the disease, you can use 20% chlorothalonil (i.e. triadimefon) as a pesticide and spray it in appropriate amounts. You can also use a suspension of 20% triadimefon and sulfur. Since the plant's own drug resistance will have a certain impact on the effectiveness of the agent, we can also use 12.5% amylopectin emulsifiable concentrate instead of the above-mentioned drugs for treatment.

2. Black spot disease

1. Symptoms

As the name suggests, black spots appear on the plants, and purple-brown, reddish-brown and small dots appear on the leaves and buds, which then spread to form spots.

2. Solution

Spraying agents: You can use carbendazim, methyl thiophanate, daconil, etc.

3. Anthrax

1. Symptoms

This symptom is somewhat similar to black spot. Most of the anthracnose lesions are distributed in a semicircular shape on the edge of the leaves. The lesions themselves transition from light brown to dark brown from the middle to the edge. In the later stage of the disease, small black spots will appear.

2. Solution

(1) Try not to place the plant in a tightly humid area, as excessive moisture can easily lead to the production of pathogens. In addition, it is necessary to write on paper in time to prevent the branches from being too dense and affecting ventilation and light transmittance. The diseased and fallen leaves should be pruned and cleaned up in a centralized manner, and it is best to burn them.

(2) If the disease is found, drugs such as 75% thiophanate-methyl powder and 20% thiophanate-methyl suspension can be used to kill the virus.

4. Leaf rust

1. Symptoms

This disease is relatively common for roses, and the pathogen will invade leaves and new branches, causing leaves to fall or even death, so timely measures must be taken.