What is causing the spots on the rose leaves?
If you want to know the introduction of green plants and flowers about why spots appear on rose leaves, the following article will be introduced by the editor for netizens.
Recently, many flower enthusiasts have found that many spots have appeared on their rose leaves. What is going on? The high incidence of spots on rose leaves during this period is mainly due to the following two reasons.
What is causing the spots on the rose leaves
1. -- Sunburn or Burn --
The symptoms of sunburn and burn on roses are very similar, mainly manifested as yellow-brown spots all over the leaf surface, especially obvious in the mesophyll part, some in patches, and some spots distributed in a dot-like pattern.
Improperly spraying foliar fertilizer is most likely to cause leaf burn, especially recently when the weather has become cool, many enthusiasts are eager to apply fertilizer to their roses. If foliar fertilizer or medicine is sprayed in the morning and the sun is strong at noon, burns can easily occur.
Moreover, sunburn is also very common during this period. Many flower enthusiasts may not understand why there is no sunburn in summer but sunburn in autumn? This inevitably involves the change in light.
Although the light in autumn is relatively softer than in summer, there is often a period of cloudy and rainy weather when autumn begins, which helps to lower the temperature. However, after consecutive rainy days, roses lack sunlight, and their leaves are full of water. When the weather clears up and the sun becomes scorching, the change in soil sunlight can easily cause rose leaves to be unable to adapt immediately, leading to sunburn.
Actually, there is no need to worry too much about sunburn on rose leaves in autumn. If the sunburn is not severe, the leaves can be retained for photosynthesis. Severely sunburned leaves can be removed.
2. -- Thrips Pest --
Autumn is the peak season for thrips. Since thrips are insects that are active at night and dormant during the day, they are rarely seen during the day, which can lead to confusion when thrips infestations occur.
Minor thrips infestations can manifest as malformed new leaves, brown scars on the back of leaves, or new buds turning black before they grow. In severe cases of thrips infestation, you can see that the top of the new branches of roses has small black leaves that do not grow, and the old leaves have scars all over the back.
Actually, thrips not only harm roses but can also harm many other plants, such as bougainvillea and hydrangeas, causing similar issues like malformed new buds.
For thrips infestations, it is recommended to prevent and control them regularly. Thrips start from April and continue to exist throughout the season, with the most severe damage in summer and autumn. If you want roses to bloom well in autumn, it is necessary to prevent and control thrips infestations in summer and autumn.
On the balcony garden, you can hang yellow and blue boards, as thrips are attracted to blue and yellow, which can effectively control the number of thrips. The simplest method of control is chemical treatment, with suggestions to alternate between dinotefuran and acetamiprid every 10-15 days. The spraying should be done in the evening for better thrips control. If sprayed in the morning or during the day, the insecticidal effect will be relatively poorer. For more rose care methods, you can refer to the introduction in the book "How to Grow Roses from Scratch."
The above is an explanation of what is causing the spots on rose leaves and a specific introduction, for reference by netizens.