What are the main pests and diseases of roses?

Roses mainly include anthracnose, black spot, powdery mildew, leaf spot and so on. Anthracnose and powdery mildew are more serious.

1. Anthracnose

(1) symptom characteristics

The lesion is semicircular at the edge of the leaf, with dark brown at the edge and brown to light brown in the middle, and there are small black spots on the lesion in the later stage. Bacteria overwinter on diseased leaves. Under warm and humid conditions, spores germinate and invade leaves. Too dense clusters, long moisturizing time, easy to get sick. Anthracnose occurs sporadically, and it can be treated at the same time when controlling black spot and leaf spot.

(2) Prevention and control methods

Clear the garden in time in late autumn and early winter, collect diseased leaves and burn them centrally. Strengthen maintenance, trim properly, and remove too dense branches to make ventilation and light transmission good. When necessary, spray 500 times of 20% dinotefuran suspension or 600 times of 78% Bohmanzin wettable powder, 600 times of 75% Dyclonine (chlorothalonil) wettable powder, 50% Prochloraz wettable powder or 1000 times, and 25% charcoal.

2. Powdery mildew

(1) symptom characteristics

Leaves, petioles, shoots and buds can all get sick. Irregular white powdery mildew spots appear on the adult leaves, and the diseased leaves gradually turn brown from the tip or edge of the leaves, resulting in the whole leaves drying up and falling off. The young leaves are infected with chlorotic macula, which gradually expands and the edge is not obvious. White powder spots are produced on both sides of the tender leaves, and the leaves turn light gray or purple. New leaf atrophy deformity. After the petiole and new shoots were infected, the internodes became shorter, the stems became thinner, some diseased branches dried up, and the diseased parts were covered with white powder. When the bud is infected, the bud and pedicel are covered with white powder, and the calyx, petals and pedicel are deformed or even shrunk.

(2) Prevention and control methods

Select varieties resistant to powdery mildew. When pruning in winter, pay attention to cutting off diseased branches and buds. Apply less nitrogen fertilizer and more phosphorus and potassium fertilizer during the onset period to improve the disease resistance. Pay attention to ventilation and light transmission, and drain water in time after rain to prevent moisture retention, which can reduce the incidence. Spraying 20% triadimefon emulsifiable concentrate or 20% triadimefon sulfur suspension concentrate with 0/000 times of/kloc-and 50% carbendazim wettable powder with 800 times of/kloc-at the initial stage of onset. In case of resistance to the above fungicides, it can be sprayed with 12.5% myclobutanil EC or 3000 times of 30% Teflon wettable powder instead. Before germination in early spring, spray Bomei 2 ~ 3 degree stone sulfur mixture or 45% crystal stone sulfur mixture 40 ~ 50 times to kill overwintering bacteria.

(2) Insect pests

The species, damage characteristics and control methods of rose pests are the same as those of rose.