Tomato
Fusarium Stem Rot
Fusarium solani
Fungus
In a Nutshell
- Clearing of veinlets.
- Chlorosis of leaves.
- Browning of vascular system.
- Stunted growth.
Can also be found in
Tomato
Symptoms
Clearing of veinlets and chlorosis of leaves are the initial disease symptoms. In young plants, symptoms consist of veinlet clearing, following by drooping of petioles. Yellowing is first observed on lower leaves. These leaflets wilt and die eventually, spreading the symptoms to subsequent leaves. At a later stage, the browning of the vascular system occurs. The lower leaves and later all leaves of the plant will drop off. The plants become stunted and die. Soft, dark brown or black cankers appear on the stem, usually at nodes and wound sites, causing girdling of the stem. The lesions develop light orange-coloured, very small, flask-shaped fruiting structures of the fungus (perithecia). White-cottony fungal growth may form on the plant. The roots, when infected, become dark brown, soft and water soaked. Pepper fruits might develop black, water-soaked lesions beginning at the calyx.
Recommendations
Organic Control
Several biological control agents, including bacteria and nonpathogenic strains of F. oxysporum that compete with the pathogens, have been used to control Fusarium wilt in some crops. Trichoderma viride @ 1% WP or @ 5% SC can also be used to treat the seeds (10g/kg seed). Other products based on Bacillus subtilis, Pseudomonas fluorescens are also effective. Trichoderma harzianum can be applied to the soil.
Chemical Control
Always consider an integrated approach with preventive measures together with biological treatments, if available. Apply soil-based fungicides on contaminated locations if no other measures are effective. Drenching the soil with Copper Oxychloride @ 3g/l of water before sowing/transplanting is also effective. Other products based on Carbendazim, Fipronil, Fluchloralin can also be applied to limit the disease spread.
What caused it?
Fusarium solani is a fungus that grows in transport tissue of plants, affecting water and nutrient supply. Plants can be infected directly via their root tips or through wounds in the roots. Once the pathogen has become established in an area, it stays active for several years as it can create overwintering spores. Soil-borne diseases survive in soil and spread through seed, soil, water, seedling, workers, irrigation water and wind (by carrying infected plant debris). The fungus is a serious disease-causing organism that affects various hosts. If infestation happens at flowering stage, serious yield loss can be expected. Stem cankers restrict the upward flow of water, which causes wilting and eventually the death of plant. Fusarium solani can colonize dead or dying plant tissues and actively ejects spores nightly. Favourable conditions of the fungi are relatively high soil moisture and soil temperature. Poor water drainage or overwatering support the disease spread.
Preventive Measures
- Plant only healthy plants from the available resistant varieties, such as Phule Jyoti and Phule Mukta.
- Monitor the plants for symptoms, such as wilting or stem lesions.
- Handpick and remove affected plants carefully.
- Discard them by either placing them in a landfill or burning them far away.
- Keep your equipment and tools clean, particularly when working between different fields.
- Avoid damage to the plants during field work.
- Good crop hygiene and pruning by clean cutting can help control the disease.
- Adjusting the soil pH to 6.5-7.0 and using nitrate rather than ammonium as nitrogen sources can reduce the severity of the disease.
- In greenhouses, use precisely adjusted drip irrigation.
- Avoid use of excessive fertilizer concentration.
- After harvest, remove plant debris and burn them.
- Keep in mind that the rotting can continue in storage.
- Disinfect the seedbeds by covering the area with black plastic foil under direct sunlight for a month.
- Follow crop rotation to reduce levels of fungi in the soil.
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