Prevention and Treatment Methods for Rose Black Spot Disease
An article about the prevention and treatment methods of rose black spot disease in flower planting, the following is an introduction by the editor.
Learn these two small actions for the prevention and treatment of rose black spot disease, and the effect doubles!
Raindrops outside the window hit the leaves of the rose and fall into the potting soil, splashing countless tiny droplets that are then sprayed onto the lower leaves of the rose, what a poetic scene...
Stop, stop, stop! The price of poetry is rose black spot disease! Can you still feel poetic when you see the black spots on the rose leaves? Recently, there has been a lot of rain, and many flower friends have found their roses infected with black spot disease, so today let's talk about the treatment methods for black spot disease.
Symptoms of Black Spot Disease
Many新手 flower friends think they have black spot disease when they see yellow leaves with spots, but that's not the case. When the old leaves first turn yellow and then have a few black spots, it is usually natural yellowing due to metabolism.
The main manifestation of black spot disease is the appearance of irregular black-brown spots on the leaves of roses, and as the disease progresses, the spots will gradually expand, and the leaves of roses will turn yellow and are easy to fall off.
In severe cases of black spot disease, the entire plant's leaves may fall off, leaving only bare stems, and at this point, if not managed properly, the rose is prone to withering, and even if it doesn't wither, it will severely affect the growth of the rose.
So how do we prevent and treat rose black spot disease?
First, we need to understand the conditions under which rose black spot disease occurs. The disease is most likely to break out in a hot and humid environment, especially in rainy seasons. Outdoor roses are particularly susceptible to infection during prolonged rainy periods.
Indoor roses on a balcony, which do not get rained on, rarely have black spot disease, but that doesn't mean they never get it. After all, we still water them. However, if roses that do not get rained on get black spot disease, simply remove the infected leaves and spray with a fungicide like carbendazim or a 200-fold alcohol solution to solve the problem.
So how do we prevent and treat outdoor roses? If you live in a region with a lot of rain, you definitely need to use chemical prevention.
Prevention should start in the spring, applying carbendazim or mancozeb every 15-20 days. After the first bloom in the spring, the preventive measures should be intensified because May is when temperatures gradually rise, there's more rain, and the roses are weakened after blooming, making them more susceptible to black spot disease.
After the roses bloom, when the weather is clear, the interval for spraying can be controlled at 15 days, but during rainy seasons, it needs to be adjusted according to the weather.
During consecutive rainy days, after every 4-5 days of rain, you should immediately spray after the rain stops. However, at this point, you can't just use carbendazim or mancozeb; you need to add stronger fungicides, such as myclobutanil, pyraclostrobin, or difenoconazole.
Here are two points to note:
1. When applying the fungicide, first pre-dilute the medication with a small amount of water, then add it to the spray tank and further dilute before spraying. 2. When spraying the fungicide solution, focus on the lower leaves of the rose, the soil surface, and the inner leaves, as these are the areas where black spot pathogens are more concentrated.
This season, not only is black spot disease prevalent, but thrips and caterpillars are also at a high incidence. When spraying, you can combine multiple medications to save time and effort. In the book "How to Grow Roses from Scratch," a comprehensive prevention plan is provided based on the occurrence patterns of various diseases and pests, which you can refer to and apply to ensure the healthy growth of roses.
The above introduction to the specific methods of preventing and treating rose black spot disease, hoping to bring some floral knowledge to flower enthusiasts.