Do roses have thorns?
This article will give you a detailed explanation of whether roses have thorns and whether they often get sick. Let's learn about it together.
##Rose thorns: Protection mechanism and variety differences Rose plants do generally have a spin-like structure, which is a defense mechanism for their long-term natural evolution. From a botanical point of view, the "thorn" of rose is actually a specialized epidermal appendage called a thorn. These spines are differentiated from epidermal cells and are mostly hook-shaped or cone-shaped. They are hard and sharp. The length is usually between 3 and 15 mm, and some varieties can even reach 2 cm.
The number and distribution of rose thorns of different varieties showed significant differences. Wild rose varieties such as Rosa rugosa usually have dense and sharp thorns, with 3-7 thorns radiating in almost every stem node. After artificial breeding of modern rose varieties, the number of thorns in many varieties has been greatly reduced. For example, Pink Peace, the "Peace" rose, only retains a small number of thorns at the base of the stem. It is worth noting that certain horticultural varieties such as 'Zephirine Drouhin' are almost spinless and are particularly suitable for garden planting and ornamental. The growth of rose thorns has obvious age regularity. The thorns on young branches are the sharpest and most numerous. As the degree of lignification of branches increases, the thorns on old stems will gradually fall off or become passive. This age difference suggests that the main function of thorns is to protect growing sites from grazing animals.## Common diseases and control methods of roses Powdery mildew is the most common fungal disease of roses. It is caused by Sphaerotheca pannosa var.rosae and mainly affects young leaves, flower buds and twigs. The initial stage of the disease appears as white powdery spots, which will cover the entire leaf surface as the disease progresses, causing the leaves to curl and deform. Control measures include: selecting disease-resistant varieties such as 'Bonica'; improving ventilation conditions; spraying 1000 times of 25% triadimefone wettable powder in the early stage of the disease, once every 10-15 days, for 2-3 times in a row. Black spot disease Diplocarpon rosae is another major threat. The disease is characterized by black round spots 2-12 mm in diameter on leaves with radial edges, which in severe cases leads to early defoliation. The pathogen overwinters in fallen leaves, so it is crucial to completely eliminate the disease in autumn. Chemical control can be used to spray 70% thiophanate methyl wettable powder at 800 times, or 12.5% diniconazole wettable powder at 3000 times. Rust Phragmidium mucronatum is characterized by orange powdery spore piles on the back of the leaves, which can cause yellowing and shedding of the leaves in severe cases. This disease spreads rapidly in humid environments, and the key to prevention is to reduce planting density to ensure good ventilation. Prevention and control agents can be used to spray 15% triadimefone wettable powder with 1000-1500 times liquid.## Identification and comprehensive management of rose pests Aphids are the most important piercing and sucking pests in rose. Common species include rose long-siphum rosae and cotton aphid Aphis gossypii. They gather on young shoots, flower buds and leaf backs to suck juice, causing the leaves to curl and deform, and the honey dew they secrete can induce coal pollution disease. Control methods include: protecting natural enemies such as ladybugs and laceflies; spraying 10% imidacloprid wettable powder with a solution of 2000 times; and hanging yellow sticky insect boards to trap and trap winged aphids. The red spider Tetranychus urticae breaks out severely in the dry and hot seasons. Yellow-white dots appear on the early leaves. In severe cases, the entire leaves turn yellow and fall off, and red dots and spider silk can be seen on the back of the leaves. Prevention and control measures include: regular foliar spraying during high temperature and drought seasons; release of predatory mites; spraying 20% pyridaben EC at 2000 times or 1.8% avermectin EC at 3000 times. Rose-stalk wasp Arge pagana larvae will drill into the branches and cause damage to the upper branches, causing wilting and death. Control methods include: cutting off and destroying damaged branches in time; turning the soil in winter to eliminate overwintering larvae; spraying 2.5% bromine * ester emulsifiable concentrate at 2500 times during the adult period.## The key maintenance points for the healthy growth of roses Soil conditions are the basis for cultivating roses. The ideal cultivation substrate should have: slightly acidic pH of 6.0-6.5; rich in humus organic matter content>3%; it is recommended to add 30% perlite or coarse sand for good drainage. The depth and diameter of the planting hole should be no less than 50 cm, and the bottom layer should be paved with 10 cm gravel as a drainage layer. Scientific watering management can significantly reduce the incidence of diseases. The basic principles include: watering in the morning to dry the leaves in time; avoiding direct watering of the leaves; and keeping the soil moist but not stagnant water. Water water 2-3 times a week during the high temperature period in summer, and water it thoroughly until 30 centimeters of soil layer is moist each time. Pruning technology directly affects plant disease resistance. Heavy pruning in winter requires retaining 3-5 main branches and 3-5 bud points per branch; light pruning in summer mainly removes residual flowers and thin branches. The trimming tools must be disinfected with 75% alcohol, and the incision should have a 45-degree slope to prevent water accumulation. The fertilization plan should adopt the "base fertilizer + top dressing" model. The base fertilizer is mainly decomposed organic fertilizer at 5-10kg/plant. During the spring germination period, nitrogen, phosphorus and potassium compound fertilizer is applied at 15:15:1550g/plant. Additional phosphorus and potassium fertilizer is applied before and after flowering to promote flowering. Pay attention to water immediately after fertilizing to prevent root burning.## Variety selection and environmental control to improve rose resistance Selecting disease-resistant varieties is the most economical control method. Black spot resistant varieties include 'Knock Out','Carefree Wonder', etc.; powdery mildew resistant varieties include'Bonica'and'The Fairy'; and high rust resistant varieties include'Rugosa'series. These varieties can maintain good growth even under unfavorable conditions. Reasonable planting density can create a microclimate that is not conducive to the spread of diseases. The plant spacing of shrub roses should be maintained at 80-100 cm, and 1.5-2 meters of space should be reserved for vine roses. Ideal lighting conditions are at least 6 hours of direct light per day to avoid shaded environments. Companion plant configurations can form a natural protective barrier. Aromatic plants such as ruta and sage can repel a variety of pests; root exudates of calendula and marigold can inhibit soil pathogenic bacteria; mint plants help reduce aphid harm. This ecological planting model is more conducive to maintaining ecological balance than single cultivation.
The above [] introduction of all the contents of whether roses have thorns and whether they often get sick are for your comprehensive understanding and reference!