Bean treatments, most common diseases and pests of this vegetable

beans phaseolus vulgaris

The bean (Phaseolus vulgaris) is a herbaceous, annual, climbing plant which originated from Central America and South America, where the Aztec tribes would plant it since ancient times. It was brought to Europe in the 16th century by the Spanish and Portuguese. The bean was been widely harvested since the 18th century, in the hillocks and plain field areas. There are 2 types of bean plants: a type which grows irregularly (crawling bean) and a type which has a limited growth (bush). The bean is an extremely popular plant and it is currently being used throughout the world as a nutritious food. It is an important source of proteins, vitamins (A, B6, C and K), calcium, magnesium, folic acid, iron, phosphorus, zinc and potassium.

Main diseases

Viruses:

Bean yellow mosaic virus

This is recognizable as the leaves grow small, yellow spots, which are located next to the leaves’ veins. These yellow areas can be the size of a whole leaf in case the disease attack a sensitive species. The attacked plants stop growing and have small bean pods.

beans phaseolus vulgaris yellow mosaic virus

 

 

 

 

 

 

 

Prevention and control measures:

  • Using healthy and certified seeds;
  • Destroying the plant residues after harvesting;
  • Early sowing is recommended;
  • Taking out the affected plants from the crop;
  • Using only resilient species;
  • Applying pesticides in order to keep the aphids population under control;

Common bean mosaic virus

The symptoms of the disease are visible between 18 and 36 degrees Celsius. The attacked leaves grow bright green or matte spots, these are in contract with the healthy areas. The plants remain small, have a slow blossoming and grow small and malformed bean pods.

 

 

 

 

 

 

 

Prevention and control measures:

  • Using healthy seeds;
  •  Destroying the plant residues after harvesting;
  • Taking out the affected plants from the crop;
  •  Using only resilient species;
  •  Applying pesticides in order to keep the aphids population under control;

Bacteriosis:

Bean blight caused by Xanthomonas campestris pv phaseoli

This disease manifests throughout all the stages of the plant development, from the first sprouts until the moment the beans are harvested. The plant has small, circular spots or irregularly shaped ones with a yellow-brown color and moist aspect. The leaves have pointy spots of a green to yellow color, which in a high humidity environment can host the body of the bacteria. On the stems, the disease is visible as reddish-brown stripes appear, which lead to wilting of the stem tissues. As a cause of the infection, the beans remain small and wrinkled and have yellow spots, which eventually turn brown.

 

 

 

 

 

Prevention and control measures:

  • Using healthy seeds;
  • Destroying the plant residues after harvesting;
  •  Chemical treatments, using Champ 77 WG, Zeama bordeleza, Melody Compact 49 WG, Funguran OH 50 WP, Copernico Hi-Bio;

Halo blight of bean caused by Pseudomonas syringae pv phaseolicola

This disease manifests throughout all the stages of the plant development, from the first sprouts until the moment the beans are harvested. The affected plants grown small, necrotic spots with a yellow outline. The bacteria prefers a high humidity atmosphere. The attacked plants remain small, they wilt and never grow bean pods.

 

 

 

 

 

 

Prevention and control measures:

  •  Using healthy seeds;
  •  Destroying plant residues after harvesting;
  • Chemical treatments, using Champ 77 WG, Zeama bordeleza, Melody Compact 49 WG, Funguran OH 50 WP, Copernico Hi-Bio;

Mycosis:

Anthracnose of bean caused by Colletotrichum lindemuthianum

The disease manifests in high humidity areas or during excessively rainy seasons. This disease can attack from a very early of the plant. Small, dot looking like spots appear on the cotyledons, the roots are rotten. When attacking grown leaves, the veins turn brown. The symptoms of the disease are visible on the back side of the leaves. The affected areas wilt and fall off the plant. The bean pods get yellow spots with a reddish-brown outline. In the proximity of these spots, the tissues are sunken. The attacked bean pods are sterile or they form beans that cannot be consumed. The fungus can live on vegetal residues and on infected seeds. The attack grows when there are between 13-27 degrees Celsius.

 

 

 

 

 

 

 

Prevention and control measures:

  • Using healthy seeds;
  • Crop rotation (beans can only be planted on the same soil once every 3-4 years);
  • Plating only resilient species;
  •  Destroying plant residues after harvesting;
  • Chemical treatments, using Dithane M45, Topsin, Merpan 50 WP, Captan 80 WDG, Melody Compact 49 WG;

Bean rust caused by Uromyces appendiculatus

The attack on the plant is visible during early spring, when the leaves get yellow spots, visible on both sides of the leaf. Next to the spots, you can see the fungus growth, in the form of white colored spores. During June-July, the leaves will have yellow spots, which contain reddish-brown and dusty dots, which represent the summer spores. During August, the leaves will have black, dusty spots, which will lead to a rapid wilt. If the specie is sensitive, the fungus can also attack the bean pods, jeopardizing their quality. The fungus can live on the vegetal residue from the soil; during vegetation the fungus is spread thanks to its spores which can be carried away by wind, or water, etc.

 

 

 

 

 

 

Prevention and control measures:

  • Destroying the plant residues after harvesting;
  • Chemical treatments, using Polyram DF, Ortiva 250 SC, Score 250 EC;

Fusarium root rot caused by Fusarium solani

The young leaves grow small, faded spots, Adult leaves turn brown and wilt. As the disease evolves, it leads to wilting of the entire plant.

The first symptoms are wilting of the ground leaves, most of the time, only on one side of the plant. The attacked leaves turn brown and fall off, but, during time, the entire plant can die.

 

 

 

 

 

Prevention and control measures:

  •  Taking out the affected plants from the crop;
  • Using only treated seeds. For more information about disinfecting and treating seeds, click here;
  • Chemical treatments, using Topsin 70 WDG and Topsin 500 SC. Mix 5 grams or 10 grams of the product with 10 liters of water and spray each plant with about half a liter of that mixture.

Powdery mildew caused by Erysiphe-polygoni

This disease can affect all the shoot system of a plant (stem, leaves, sprouts, etc.). On the upper side of the leaves, brown spots can be visible. The spots turn gray and after the spores appear, it turns dusty. The disease can attack the entire leaf. The affected tissues die and fall off the plant.

 

 

 

 

 

 

Prevention and control measures:

  •  Planting only resilient species;
  • Destroying the plant residue after harvesting;
  • Chemical treatments, using  Topas 100 EC, Kumulus DF, Ortiva 250 SC, Thiovit Jet 80 WG, Systhane Plus 24 E;

Main pests

The bean weevil (Acanthoscelides obtectus) is the most important pest of the beans. The adults lay the eggs, in the field, in the bean pods. The larvae get into the underdeveloped beans. They also feed with the whole bean, also damaging the cotyledons and the embryo. The seeds can be completely destroyed. The eaten beans cannot be consumed any longer and they have also lost their germination attributes.

 

 

 

 

 

Prevention:

  • Applying Decis Mega EW 50, Mavrik 2 F, Fastac Active, Reldan 22 EC during the vegetative period, or treating the warehouses with K-Obiol.

Greenhouse firefly (Trialeurodes vaporariorum)

This pest grows in greenhouse conditions year-round, in the field it can only grow during summertime. It can have 3-6 generations per year, inside a greenhouse, when all the conditions are favorable. The adults and larvae colonize the leaves and sometimes and sprouts. As a result of the attack, the leaves etiolate, dry out and fall off.

 

 

 

 

 

 

Prevention:

  • Destroying the vegetal residue after terminating the crop;
  •  Disinfecting the greenhouses and solariums before plating a different species;
  •  Treatments using Decis Mega 50 EC (0.25 l/ ha), Actara 25 WG ( 0.2 kg/ha), Confidor Energy (1.3 l/ha), Mospilan 20 SG (1.5 gr/ 6 l water), Movento 100 SC;
  • Using sticky traps.

Red spider mite (Tetranychus urticae)

It has 6-10 generations per year and it would pass the winter in an adult stage, mostly females (males being rare) and under fallen off barks or leaves, on dried out weeds or under the superficial soil layer. The affected leaves usually wilt and fall off and this can lead to a tree losing up to 80-100% of its foliage. As a consequence of the attack, the sprouts would stop growing and the fruits would get ripe earlier than they should.

Prevention:

  •  Treatments with Vertimec
    (1 l/ha), Nissorun 10 WP (5 g/12 l water), Envidor 240 SC, Millbeknock EC;

Aphids are a polyphagous specie that migrates from one plant to another or from one specie to another. These grow on spontaneous plants and then migrate to crops. They can be seen as colonies on the back of the leaves, on the flowers or on the small blooms from the sprouts. They sting the plant and drink the juice that flows through a plant’s vascular system, causing stress to the plant. They can also kill the plant in case of a severe attack.

 

 

 

 

 

 

Prevention:

  • Treating areas with Decis
    Mega 50 EC (0.2 l/ha), Confidor Energy (0.6 l/ha), Mospilan 20 SG (1.5 gr/ 12 l
    water), Actara 25 WG;
  •  Using sticky traps.

Painted Lady (Vanessa cardui)

This is a polyphagous specie. This pest is present in areas where the climate is moderate. This butterfly can fly while it rains and its larvae grow quickly. The butterfly normally has 3 generation per year. The adults lay the eggs on the upper side of the leaves. After they hatch, the larvae feed on the leaves and can lead to plant defoliation.

 

 

 

 

 


Prevention:

  • Treatments using Decis Mega EW 50, Fury 10 EC, Kaiso Sorbie, Novadim Progress, Mospilan 20 SG;

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