Reasons for the yellowing of rose leaves
Core introduction: Experience in green plant maintenance for the reasons of yellowing of rose leaves, the following editor will answer your questions in detail
Reasons for yellowing of rose leaves How to deal with yellowing of rose leaves
Recently, in the Aiwen Circle, quite a few flower friends have consulted about the problem of yellowing leaves of roses. So today, let's summarize the common reasons for yellowing leaves of roses for your reference.
Common reasons for yellowing of rose leaves
In spring, it is originally the vigorous growth period of roses. However, in the budding stage of roses, if there were no blind buds removed before, roses are more prone to metabolic yellowing of leaves.
This kind of yellowing mostly occurs in the inner and bottom parts of the plant, as well as the bottom leaves of new branches. Because these leaves have been growing for a long time and are in the bottom, the ventilation and sunlight are very poor. After the roses bloom, these leaves have completed their mission and naturally turn yellow and fall off.
The yellowing leaves of natural metabolism do not need to worry, just remove them in time. However, some yellowing leaves are pathological and need to be treated.
1. Black spot yellow leaves
Black spot is one of the most common diseases of rose flowers. If prevention was not paid attention to before, most of them have been attacked by black spot disease.
In the early stage of black spot disease, it only forms black spots on the leaves. If not discovered and treated in time, the black spot disease will further develop or infect other healthy leaves, leading to yellowing of the leaves and large-scale falling off.
Severe black spot disease can make the rose become bare, severely affecting the growth of rose flowers. When black-brown spots appear on the leaves of roses, be sure to remove the diseased leaves in time and spray with carbendazim and flusilazole for treatment. If the black spot disease is severe, it is necessary to use continuous medication, once every 5-7 days, alternating between carbendazim flusilazole and mancozeb myclobutanil or nande stable until the lesion does not expand, indicating recovery.
Prevention is key for black spot disease. It is important to pay attention and spray preventive medication in time. The commonly used preventive fungicides are carbendazim and mancozeb, which are more protective.
2. Iron deficiency yellow leaves with black spot disease
Iron deficiency yellowing is also a common situation in rose leaves, manifested as normal old leaves and light yellow new leaves. The reason for iron deficiency in roses is mostly due to root damage and poor nutrient absorption.
For example, root damage caused by excessive fertilization or main stem damage by borers can lead to poor nutrient transport, causing iron deficiency in roses.
When correcting yellowing leaves, it is recommended to use chelated iron spray, which has a relatively quick effect. Note that ferrous sulfate should not be sprayed on leaves, as a low concentration is not effective, and a high concentration can leave unsightly rust spots that cannot be washed off. Root application of ferrous sulfate to supplement iron is also poor because the root cause of iron deficiency may well be due to poor root absorption.
3. Red spider yellow leaves
Red spider-induced yellowing is also quite common at this time, but it is often not easily detected in the early stages, or even when abnormalities are detected, they can be difficult to confirm.
Red spiders often gather on the back of rose leaves, absorbing sap, and from the front of the rose leaf surface, they appear as dense, pinpoint yellow spots, which are not very noticeable at first and can be easily overlooked.
In the face of red spiders, we must detect and treat early. At this time, we can remove some of the old leaves near the potting soil to strengthen the ventilation at the bottom of the plant and maintain a comfortable relative humidity of the environment.
Red spiders are most likely to occur in dry and poorly ventilated environments. If it is dry and hot where you are, it is recommended to spray preventive medication regularly, focusing on the back of the leaves and the surface of the potting soil.
If there are already red spiders, it is recommended to first rinse the rose leaves with a high-pressure water gun and then spray insecticides for mite control, such as damalin, jinmanzhi, or螺螨酯. Mixing two types of miticides can achieve better therapeutic effects. There are still many pest and disease problems in roses, and you can refer to the introduction in the book "How to Start from Scratch to Burst Roses" for more pest and disease control methods.
4. Drought yellow leaves
Drought yellowing is also very common in spring, especially for newly planted rose seedlings. I have directly encountered several flower friends who bought rose seedlings at home, transplanted them to the ground, watered them once, and found that they all turned yellow after three or four days. In fact, this is due to drought.
Newly transplanted seedlings have not yet extended their roots and the water consumed is still from the original soil clump. Since our cultivation soil is very breathable, it is normal to water once a day during this season. After about 10 days, when the new roots extend into the soil, we can manage them more loosely.
This is the case for both ground planting and newly repotted plants. When checking the moisture of the potting soil, we should look at the moisture of the original soil clump, not the new soil. If the original soil clump is dry, it needs to be watered. Sometimes, if the potting material is too dry, the water quickly leaks out, and at this time, it is necessary to soak the pot once to allow the potting soil to absorb enough water.
This article is an original sharing by the Garden. In my public account: Garden (ilanyao), there are thousands of practical rose cultivation articles to help you avoid flower pits!
The above is a detailed introduction to the reasons for the yellowing of rose leaves and how to deal with yellowing leaves of roses. Do you know now?