Common diseases of Catharanthus roseus and their control methods

Black spot

Symptoms

Black spot mainly harms stems and leaves. In the early stage, black-brown spots will appear on the leaves, which will spread to form lesions. As the spots expand and increase in number, the entire leaf will die. The lesions will spread to the stems, causing the plant to fall over.

Prevention and treatment methods

Clean up diseased leaves in time and keep the surface of the potting soil clean. If you find spots on the leaves, remove them immediately to prevent them from spreading. When the disease occurs, spray the pesticide in time, choose Zineb solution, and spray both sides of the leaves.

Basal rot

Symptoms

Basal rot mainly harms the stem of the plant. The rhizome will turn dark brown, the leaves above the ground will slowly wither, the plant will fall over, and in severe cases the whole plant will die.

Prevention and treatment methods

If you find that the base of the plant is rotten, remove it and destroy it in time. Replace new soil and pots and disinfect them before use. Pay attention to hygiene when fertilizing and watering, and avoid using uncomposted fertilizers and contaminated water to water the plants. When the disease occurs, spray the pesticide in time, 1000 times diluted triadimefon and carbendazim wettable powder, or 1000 times diluted 56% Kaoshan dispersible granules, spray continuously for 4 to 5 times, dense at first and sparse at the end.

Yellowing disease

Symptoms

The leaves of the plant turn yellow due to insufficient nutrients, unsuitable environment, fungal infection and other reasons.

Prevention and treatment methods

Cut off the yellowing leaves. If the yellowing is severe, remove the plant. When propagating (seeding, cuttings), choose healthy plants as mother plants. Prevent and control insect pests, as they will form wounds on the leaves, which may be infected with pathogens.

Mosaic

Symptoms

The whole plant is diseased, patterns appear on the leaves, the plant grows poorly, the flowers are small and few, and spots and deformities appear on the petals.

Prevention and treatment methods

The mosaic virus has a strong latent ability and can overwinter on the plant, then cause disease in spring, so prevention is necessary. Spray fungicides before winter. Remove weeds and dead leaves promptly to reduce sources of infection.