How to protect stevia from diseases and pests?

In Blogs
June 21, 2021
5 min read

Wild stevia doesn’t need much protection as steviol glycoside has a substantial pest repellent effect but what about current high producing stevia breeds. Do they need protection from insects or infection? If yes, then how to protect stevia from diseases or pests?

Some of the current high producing Stevia breeds require crop protection to some extent. In general, pest and disease attack is triggered by poor growing circumstances, excessive moisture in the soil and air, weed infestation, and inadequate nutrition. The first line of defense is often good nutrition and agronomic management.

Several fungal species have been observed to infect Stevia, potentially resulting in significant production loss. The following is a list of fungal pathogens for Stevia and their diagnostic features.

How to Protect Stevia from Diseases

Alternaria Alternata

Light brown little circular specks that develop dark brown to grey and have concentric rings in a circular to irregular pattern. Large areas of necrosis can occur as spots combine.

Sclerotinia Sclerotiorum

Wilting, chlorotic leaves, necrotic leaves near the stem’s base, and bleached stems are all signs of wilting. On the stems of symptomatic plants, there are often tufts of white hyphae and big, irregularly shaped 2 to 8mm black sclerotia.

Sclerotium Rolfsii

Leaves yellowing and wilting, bleached stems, and eventually plant necrosis Early in the morning, white cord-like mycelia growth can be seen at the base of stems. Brown sclerotia with a diameter of 0.5-2mm form beside the mycelium.

Septoria Steviae

Depressed and angular foliar lesions with a gleaming olive-gray appearance. Lesions generally have a chlorotic halo and agglomerate quickly, turning necrotic and causing the plant’s leaves to fall off. In severe cases, up to 50% of the foliage can become necrotic.

Rhizoctonia Species

The sunken reddish patches on the plants’ leaves progressively get larger, killing them. Young plants are susceptible to reddish-brown to brown collar and root rots. These rots stop plants from growing normally, resulting in stunted or weakened plants. Collar callus development and thickening are also common.

Fusarium Oxysporum

Wilting, chlorosis, necrosis, premature leaf drop, vascular browning, stunting, and damping-off are all symptoms of wilting. Vein clearing on the younger leaves and drooping of the older lower leaves are the first signs of Fusarium wilt, which is followed by plant stunting, yellowing of the lower leaves, defoliation, marginal necrosis, and death.

Remedial Measures to Protect Stevia Plant from Diseases

Cultural Control

If there is any standing water in the field, make sure it is drained, weeds must be eliminated.

Until the disease is under control, neither nitrogen fertilization or organic manuring should be used. To boost immunity, apply a potash top dressing.

Biological Management

Use the following inoculants on a case-by-case basis.

  • Trichoderma harzianum/viride Trichoderma harzianum/viride
  • Ampelomyces quisqualis is a species of Ampelomyces.
  • Bacillus subtilis is a bacterium found in soil.
  • Gliocladium catenulatum is a species of gliocladium.
  • Streptomyces lydicus (Streptomyces lydicus) is a kind of

These aren’t particularly successful in terms of healing.

Control Methods that are Organically Certified

Choose one of the options below.

  • Copper oxychloride is a kind of copper salt.
  • Mixture of copper sulfate and lime

Chemical Control

Chemical control agents that are effective include:

  • Chlorothalonil
  • Propiconazole
  • Trifloxystrobin
  • Captan
  • Carbendazim

To be used in the recommended amounts.

How to Protect Stevia from Pests

The following are the most prevalent insect pests of stevia and their treatment measures:

Cutworm

Cutworms are moth larvae that spend the day hiding under litter or soil and emerge at night to feast on plants. Cutworm refers to a larva that attacks the stem and cuts it down. Cutworms are caterpillars, not worms, according to biology.

Control Measure:

Biological

Inoculants of Bacillus thuringiensis var. Kurstaki can be used as sprays or baits.

Chemical

Carbofuran 3G or Phorate 10G is applied to the soil and then irrigated.

Aphids

Aphids are little, soft-bodied insects with long, slender mouthparts that pierce stems, leaves, and other fragile plant parts to extract fluids. Although many aphid species are difficult to differentiate, most aphid species require comparable treatment.

Control Measure:

Biological

Use pesticides based on mineral oil plus soap emulsion or neem oil to protect stevia from aphids.

Chemical

Imidacloprid, malathion, and acephate are examples of synthetic pyrethroids like permethrin, as well as traditional insecticides like Imidacloprid, malathion, and acephate.

White Fly

Whiteflies are sap-sucking insects that congregate in large numbers on the undersides of leaves. Great clouds of winged adults fly into the air when afflicted plants are disturbed. Plants are harmed by both nymphs and adults sucking the juices from new growth, resulting in stunted development, leaf yellowing, and lower yields. Plants become feeble and disease-prone as a result of this.

Control Measure:

Biological

Use pesticides based on mineral oil plus soap emulsion or neem oil to protect stevia plants from white fly.

Yellow sticky traps

Chemical

Use pyrethroids such as dichlorvos, imidacloprid, or synthetic pyrethroids.

Red Spider Mites

By piercing plant leaf cells with their mouthparts, red spider mites feed on the contents of the cells. On leaves where the cells have died, this results in a fine brown speckling effect. Adult mites also spin a delicate silk webbing on the surface of the leaves. This can cover the majority of the plant if the infestation is severe.

Control Measure:

Biological

Use pesticides based on mineral oil + soap emulsion or neem oil.

To physically remove the nites, wash the plants.

Chemical

Spray insecticides based on dicofol, dinocarp, abamectin, bifenazate, hexythiazox, or spiromesifen.

Thrips

Thrips are slender insects with fringed wings that are small and thin. Stippling, discolored flecking, or silvering of the leaf surface results from their puncturing the epidermal (outer) layer of host tissue and sucking out the cell contents. Thrips feeding is generally accompanied by black frass particles that look like varnish (excrement).

Control Measure:

Biological

Use pesticides based on mineral oil + soap emulsion or neem oil.

Use Yellow sticky traps

Chemical

Use pyrethroids such as dichlorvos, imidacloprid, or synthetic pyrethroids.

Reference: Stevia Technology

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