Home › Growing Techniques › Article

A Detailed Guide to Common Primrose Diseases and Their Control Methods

Growing Techniques 0 views
Teacher Xiaohuizi now introduces the common diseases of primroses as follows
Primrose is a perennial herbaceous plant of the genus Primula in the family Primulaceae. This genus contains many species that bloom in winter and spring. The plants can produce large numbers of beautiful flowers, clustered in the center of the leaf rosette, and the flower colors are very rich. Teacher Xiaohuizi now introduces the common diseases of primroses as follows.I. Primrose Mosaic DiseaseSymptoms: A whole-plant disease caused by Cucumber Mosaic Virus (CMV). The symptoms are smaller, deformed leaves with dark green mottling or yellowing. Infected plants do not bloom, or if they do bloom, the flowers are also small and deformed, with mottling (see Figure 1). The main route of transmission is virus transmission by the green peach aphid and the cotton aphid. The main source of infection is diseased weeds in the surrounding area.Control methods: First, promptly remove weeds to reduce the source of infection. Second, aphids should be controlled early to eliminate the virus-transmitting vector.II. Primrose Brown SpotSymptoms: Mostly occurs on the common primrose (Primula malacoides). It is caused by Alternaria fungi of the Deuteromycetes. Infected plants have brown spots on the leaves. The route of transmission is that conidia are spread by wind and rain.Control methods: In the early stage of the disease, spray fungicides such as 70% chlorothalonil wettable powder at 1000 times dilution.III. Primrose Gray MoldSymptoms: One of the common diseases of primroses, occurring all over the country. After the plant is infected, the whole plant turns yellow and dies. This disease mainly infects the leaves, tender stems, flowers and other parts. It mostly occurs at the leaf tips and leaf margins. In the early stage of the disease, water-soaked spots appear on the leaves, which gradually expand, turn brown and rot. In the later stage, a grayish-yellow mold layer forms on the surface of the lesions. After the stem is infected, the lesions are brown and gradually rot. After the flowers are infected, they also turn brown, rot and fall off. Under humid conditions, a gray mold layer appears on the diseased parts, which is a major feature of this disease. The disease overwinters as sclerotia in diseased plant debris and soil. It is prone to occur when the temperature is around 20°C and the air humidity is high. It spreads through wind and rain, tools and irrigation water. In greenhouses, it is most severe in late winter and early spring.

Control methods: Planting density should be reasonable. Pay attention to ventilation and reduce air humidity. Promptly remove diseased leaves and plants to reduce the source of infection. In the early stage of the disease, spray 50% procymidone or 50% iprodione wettable powder at 1500 times dilution. It is best to alternate with 65% dimethirimol wettable powder at 500 times dilution to prevent the development of fungicide resistance.IV. Primrose Leaf SpotSymptoms: Mainly harms the leaves of the plant. The disease spreads from the lower part of the plant to the upper part. The lesions are usually 3 to 4 mm in diameter and brown. In severe cases, the diseased leaves wither and die, causing defoliation (see Figure 2). This disease is caused by Corynespora primulae. The pathogen overwinters as mycelium or conidiomata on diseased plant debris, and seeds can also carry the pathogen, becoming the primary infection source for the following year. The disease mainly spreads through conidia carried by air and rain. Reinfection is frequent during the growing season. Plants are usually susceptible to the disease under warm, humid weather and when nitrogen fertilizer is applied excessively. The disease generally begins in July and becomes epidemic from August to October.Control methods: Select and breed disease-resistant varieties, strengthen fertilizer and water management, apply more organic fertilizer and phosphorus and potassium fertilizer, and avoid excessive nitrogen fertilizer. In the early stage of the disease, spray 70% thiophanate-methyl at 1000 times dilution plus 75% chlorothalonil wettable powder at 1000 times dilution, or Bordeaux mixture at 1:1:100.V. Primrose Bacterial Leaf SpotSymptoms: It mostly occurs on leaves and receptacles. In the early stage, water-soaked irregular lesions appear along the leaf veins, then yellow and turn brown, the lesions expand, and the leaf margins dry up. In severe cases, the lower leaves wither and die.Control methods: Strengthen cultivation management, cultivate disease-free seedlings, and disinfect the seedbed soil; ventilate the greenhouse promptly to reduce air humidity. Promptly remove diseased plant debris. After the disease occurs, spray 50% copper bis(dodecylbenzenesulfonate) wettable powder at 500 times dilution, or 72% agricultural streptomycin wettable powder at 4000 times dilution.VI. Primrose Iron Deficiency ChlorosisSymptoms: The young leaves at the upper part of the plant lose green first, while the old leaves remain normal. In the chlorotic leaves, the mesophyll turns yellow while the veins remain green. In severe cases, brown spots appear at the leaf tips, and the leaves may even fall off.Control methods: The potting soil should be a loam rich in iron. Mixing ferrous sulfate and zinc sulfate into organic fertilizer can promote root development and increase the ability to absorb iron. When iron deficiency symptoms appear, spray a 0.2 to 0.5% ferrous sulfate solution, which is more effective than directly applying it to the soil.

Common Primrose Diseases and Their Control

Primrose is a perennial herbaceous plant of the genus Primula in the family Primulaceae. This genus contains many species that bloom in winter and spring. The plants can produce large numbers of beautiful flowers, clustered in the center of the leaf rosette, and the flower colors are very rich. The author now introduces the common diseases of primroses as follows.

Primrose Mosaic Disease

Symptoms: A whole-plant disease caused by Cucumber Mosaic Virus (CMV). The symptoms are smaller, deformed leaves with dark green mottling or yellowing. Infected plants do not bloom, or if they do bloom, the flowers are also small and deformed, with mottling (see Figure). The main route of transmission is virus transmission by the green peach aphid and the cotton aphid. The main source of infection is diseased weeds in the surrounding area.

Control methods: First, promptly remove weeds to reduce the source of infection. Second, aphids should be controlled early to eliminate the virus-transmitting vector.

Primrose Brown Spot

Symptoms: Mostly occurs on the common primrose (Primula malacoides). It is caused by Alternaria fungi of the Deuteromycetes. Infected plants have brown spots on the leaves. The route of transmission is that conidia are spread by wind and rain.

Control methods: In the early stage of the disease, spray fungicides such as 70% chlorothalonil wettable powder at 1000 times dilution. Primrose Gray Mold

Symptoms: One of the common diseases of primroses, occurring all over the country. After the plant is infected, the whole plant turns yellow and dies. This disease mainly infects the leaves, tender stems, flowers and other parts. It mostly occurs at the leaf tips and leaf margins. In the early stage of the disease, water-soaked spots appear on the leaves, which gradually expand, turn brown and rot. In the later stage, a grayish-yellow mold layer forms on the surface of the lesions. After the stem is infected, the lesions are brown and gradually rot. After the flowers are infected, they also turn brown, rot and fall off. Under humid conditions, a gray mold layer appears on the diseased parts, which is a major feature of this disease. The disease overwinters as sclerotia in diseased plant debris and soil. It is prone to occur when the temperature is around 20°C and the air humidity is high. It spreads through wind and rain, tools and irrigation water. In greenhouses, it is most severe in late winter and early spring.

Control methods: Planting density should be reasonable. Pay attention to ventilation and reduce air humidity. Promptly remove diseased leaves and plants to reduce the source of infection. In the early stage of the disease, spray 50% procymidone or 50% iprodione wettable powder at 1500 times dilution. It is best to alternate with 65% dimethirimol wettable powder at 500 times dilution to prevent the development of fungicide resistance.

Primrose Leaf Spot

Symptoms: Mainly harms the leaves of the plant. The disease spreads from the lower part of the plant to the upper part. The lesions are usually 3 to 4 mm in diameter and brown. In severe cases, the diseased leaves wither and die, causing defoliation. This disease is caused by Corynespora primulae. The pathogen overwinters as mycelium or conidiomata on diseased plant debris, and seeds can also carry the pathogen, becoming the primary infection source for the following year. The disease mainly spreads through conidia carried by air and rain. Reinfection is frequent during the growing season. Plants are usually susceptible to the disease under warm, humid weather and when nitrogen fertilizer is applied excessively. The disease generally begins in July and becomes epidemic from August to October.

Control methods: Select and breed disease-resistant varieties, strengthen fertilizer and water management, apply more organic fertilizer and phosphorus and potassium fertilizer, and avoid excessive nitrogen fertilizer. In the early stage of the disease, spray 70% thiophanate-methyl at 1000 times dilution plus 75% chlorothalonil wettable powder at 1000 times dilution, or Bordeaux mixture at 1:1:100.

Primrose Bacterial Leaf Spot

Symptoms: It mostly occurs on leaves and receptacles. In the early stage, water-soaked irregular lesions appear along the leaf veins, then yellow and turn brown, the lesions expand, and the leaf margins dry up. In severe cases, the lower leaves wither and die.

Control methods: Strengthen cultivation management, cultivate disease-free seedlings, and disinfect the seedbed soil; ventilate the greenhouse promptly to reduce air humidity. Promptly remove diseased plant debris. After the disease occurs, spray 50% copper bis(dodecylbenzenesulfonate) wettable powder at 500 times dilution, or 72% agricultural streptomycin wettable powder at 4000 times dilution.

Primrose Iron Deficiency Chlorosis

Symptoms: The young leaves at the upper part of the plant lose green first, while the old leaves remain normal. In the chlorotic leaves, the mesophyll turns yellow while the veins remain green. In severe cases, brown spots appear at the leaf tips, and the leaves may even fall off.

Control methods: The potting soil should be a loam rich in iron. Mixing ferrous sulfate and zinc sulfate into organic fertilizer can promote root development and increase the ability to absorb iron. When iron deficiency symptoms appear, spray a 0.2 to 0.5% ferrous sulfate solution, which is more effective than directly applying it to the soil.

Common Primrose Diseases and Their Control Figure

  Primrose is a perennial herbaceous plant of the genus Primula in the family Primulaceae. This genus contains many species that bloom in winter and spring. The plants can produce large numbers of beautiful flowers, clustered in the center of the leaf rosette, and the flower colors are very rich. The author now introduces the common diseases of primroses as follows.
  Primrose Mosaic Disease
  Symptoms: A whole-plant disease caused by Cucumber Mosaic Virus (CMV). The symptoms are smaller, deformed leaves with dark green mottling or yellowing. Infected plants do not bloom, or if they do bloom, the flowers are also small and deformed, with mottling. The main route of transmission is virus transmission by the green peach aphid and the cotton aphid. The main source of infection is diseased weeds in the surrounding area.

  Control methods: First, promptly remove weeds to reduce the source of infection. Second, aphids should be controlled early to eliminate the virus-transmitting vector.
  Primrose Brown Spot
  Symptoms: Mostly occurs on the common primrose (Primula malacoides). It is caused by Alternaria fungi of the Deuteromycetes. Infected plants have brown spots on the leaves. The route of transmission is that conidia are spread by wind and rain.
  Control methods: In the early stage of the disease, spray fungicides such as 70% chlorothalonil wettable powder at 1000 times dilution.
  Primrose Gray Mold
  Symptoms: One of the common diseases of primroses, occurring all over the country. After the plant is infected, the whole plant turns yellow and dies. This disease mainly infects the leaves, tender stems, flowers and other parts. It mostly occurs at the leaf tips and leaf margins. In the early stage of the disease, water-soaked spots appear on the leaves, which gradually expand, turn brown and rot. In the later stage, a grayish-yellow mold layer forms on the surface of the lesions. After the stem is infected, the lesions are brown and gradually rot. After the flowers are infected, they also turn brown, rot and fall off. Under humid conditions, a gray mold layer appears on the diseased parts, which is a major feature of this disease. The disease overwinters as sclerotia in diseased plant debris and soil. It is prone to occur when the temperature is around 20°C and the air humidity is high. It spreads through wind and rain, tools and irrigation water. In greenhouses, it is most severe in late winter and early spring.
  Control methods: Planting density should be reasonable. Pay attention to ventilation and reduce air humidity. Promptly remove diseased leaves and plants to reduce the source of infection. In the early stage of the disease, spray 50% procymidone or 50% iprodione wettable powder at 1500 times dilution. It is best to alternate with 65% dimethirimol wettable powder at 500 times dilution to prevent the development of fungicide resistance.
  Primrose Leaf Spot
  Symptoms: Mainly harms the leaves of the plant. The disease spreads from the lower part of the plant to the upper part. The lesions are usually 3 to 4 mm in diameter and brown. In severe cases, the diseased leaves wither and die, causing defoliation. This disease is caused by Corynespora primulae. The pathogen overwinters as mycelium or conidiomata on diseased plant debris, and seeds can also carry the pathogen, becoming the primary infection source for the following year. The disease mainly spreads through conidia carried by air and rain. Reinfection is frequent during the growing season. Plants are usually susceptible to the disease under warm, humid weather and when nitrogen fertilizer is applied excessively. The disease generally begins in July and becomes epidemic from August to October.
  Control methods: Select and breed disease-resistant varieties, strengthen fertilizer and water management, apply more organic fertilizer and phosphorus and potassium fertilizer, and avoid excessive nitrogen fertilizer. In the early stage of the disease, spray 70% thiophanate-methyl at 1000 times dilution plus 75% chlorothalonil wettable powder at 1000 times dilution, or Bordeaux mixture at 1:1:100.
  Primrose Bacterial Leaf Spot
  Symptoms: It mostly occurs on leaves and receptacles. In the early stage, water-soaked irregular lesions appear along the leaf veins, then yellow and turn brown, the lesions expand, and the leaf margins dry up. In severe cases, the lower leaves wither and die.
  Control methods: Strengthen cultivation management, cultivate disease-free seedlings, and disinfect the seedbed soil; ventilate the greenhouse promptly to reduce air humidity. Promptly remove diseased plant debris. After the disease occurs, spray 50% copper bis(dodecylbenzenesulfonate) wettable powder at 500 times dilution, or 72% agricultural streptomycin wettable powder at 4000 times dilution.
  Primrose Iron Deficiency Chlorosis
  Symptoms: The young leaves at the upper part of the plant lose green first, while the old leaves remain normal. In the chlorotic leaves, the mesophyll turns yellow while the veins remain green. In severe cases, brown spots appear at the leaf tips, and the leaves may even fall off.
  Control methods: The potting soil should be a loam rich in iron. Mixing ferrous sulfate and zinc sulfate into organic fertilizer can promote root development and increase the ability to absorb iron. When iron deficiency symptoms appear, spray a 0.2 to 0.5% ferrous sulfate solution, which is more effective than directly applying it to the soil.

Related Articles