What to do if white spots appear on chrysanthemum leaves

1. Powdery mildew

1. Reasons

This disease is caused by powdery mildew fungus. This disease is likely to occur in open-field cultivation areas in the south and in greenhouses in the north, and the pathogen will overwinter in the soil. It can occur in places with high humidity and low light, poor ventilation, and large temperature differences between day and night. The disease will be more serious if we water it too much, or the plants are planted too densely or drought occurs. In the initial stage of this disease, there will be more yellow and white powdery spots on the leaves, located on the front of the leaves, and other parts of the leaves are also easily infected, which may be fatal in severe cases.

2. Measures

First, we need to clean up the weeds that have survived the winter, and then water and fertilize it.

Secondly, you need to trim its branches and clear away its leaves so that all its leaves can receive sunlight and be blown by the wind.

Finally, we need to use carbendazim on it. It is also feasible to use 0.3 and 0.5 lime-sulfur mixture. Generally, spray once every ten days or three times in a row.

2. White rust

1. Reasons

This type of disease mainly occurs when the pathogens overwinter in the soil or on the plants, and then cause harm in the next season. It is spread through artificial field operations, and it can also be spread if the flower pots are placed too densely, and high-pressure water spraying can also spread with the water. In the early stages of this disease, small spots will appear on the leaves, which will gradually become larger and then turn light yellow-brown. If the disease is serious, the plant will die.

2. Measures

First of all, fertilizer should be applied, and phosphorus and potassium fertilizers should be increased. This will make the plant more resistant to pathogens.

Then we need to drain the water frequently and not let water accumulate in the pot. Remove weeds and clean up diseased leaves.

In the rainy season, use 65% mancozeb or 0.3 to 0.5 lime sulfur mixture at intervals of ten to fifteen days to suppress the spread of the disease. In addition, carbendazim or thiophanate-methyl can also be used.