FUSARIUM STALK ROT

The microbiological destruction of organic debris in the field is a natural process. The Fusarium fungi are members of this debris-feeding microbiological community. Sometimes unfortunately these fungi attack healthy or healthy-looking plants, and may even cause total stalk destruction.

Causal organism:
Fusarium spp. (Fusarium graminearum)
(Fusarium culmorum)
(Fusarium moniliforme)
(Fusarium semitectum) and some other species

Occurrence and importance:
The stalk rot causing Fusarium fungi are present worldwide where maize or cereals are cultivated. These pathogens are home nearly in every soil. Infection pressure during the growing season is continuously hard. Stressed (by other pathogens, draught or other factors) plants are more susceptible. Infected plants fall down, this may cause hard yield losses. Early infection is rare, but may kill out the plants. Late infection in the summer is common, the hazard of yield losses depends on the cultivated variety.

Symptoms and mistakable diseases:

Early infection usually causes a hard antocyanotic purple-red discolouration at the base of the stalk and at the nodes. Later infection causes a straw-coloured plant. The internal part of the stalk is destroyed, later the whole stem brakes to parallel parts.

 

 

 

 

Under humid conditions, a pair of pink mould rings is appears at the nodes. This ring is a typical symptom of the fusarium stalk rot. Rings may be white-pink, rarely dark red.
It depends on the species of the pathogen.
Stalk rot may be caused by other fungi too, but never as apparent mycelial rings at the nodes, so this disease is easy to identify.

 

 

Disease cycle:
The fungi winters in the soil and in the plant residues as mycelia, hard-wall developed chlamydospora or sexual body at some species. Therefore it is important to avoid cultivation without crop rotation. The fungus attacks the stalk as mycelia by spores developed in a sexual or asexual way. Loose tissues and injuries are the best gates to this infection. The pathogens feed the internal parts of the internodes, the stem will be empty. In the plant tissue, the mycelia develop chlamydospores when the feeding material is at its end. Asexual spores develop outside, at the nodes in rings. Sexual bodies and spores develop at some species on the basal part of the stalk. The genetic material of these fungi varies a lot by sexual multiplication and anastomosis between mycelia and asexual spores. Disease-inflicting species have several strains, isolates, which are difficult to distinguish. Their multiplication rate, toxin and pigment developing disposition is also varied.

Control:
Genetic control against the fusarium stalk rot is well developed and the characteristics of hybrids are published in the descriptive list of varieties in every EU state. Good resistance against the fusarium stalk rot is an important evaluation criterion, very susceptible hybrids rarely will be registered. Use of resistant hybrids is the best and easiest way of control since thus ripened yield may kept on the field.
Cultivation with crop rotation is very important. This method reduces the infection pressure and usually results much lower infection rates.
Good soil cultivation is important too. A well-ploughed plant debris is destroyed much faster and Fusarium fungi winter in this method only as mycelia. Spreading by sexual and asexual spores is prevented by well-managed soil cultivation.
Avoidance of the stressed status of crops is important too. Infection of healthy plants begins later than in stressed plants. A balanced nutrition, water supply if necessary, good soil cultivation may keep the crop healthy.
Against the fusarium stalk rot, there is no chemical treatment with spraying. Early infection is easy to prevent with seed-dressing materials. In some states in Europe, like in Hungary, seed-dressing is prescribed, except for organic cultivation.

Useful seed-dressing materials include the following:

Name of the
active ingredient
Effect method
Name of product
Used rates
TMTD Contact Royalflo 2.5 - 3.0 l/t
TMTD Contact Sacrust TMTD 5.0 l/t
Benomyl Systemic Agrocit 2.0 kg/t
Isopamphos Systemic BF-51 900 WSC 1.5 l/t
Carboxine+Others Systemic Buvisild CB 2.0 - 3.0 l/t
Carboxine+Others Systemic Buvisild CR 2.0 - 3.0 l/t
Captan Contact Buvisild K 3.0 l/t
Fludioxonil Systemic Maxim XL 035 FS 1.0 l/t
Carboxine+Others Systemic Vitavax 200 2.5 l/t
Carboxine+Others Systemic Vitavax 200 FS 2.5 l/t
Carboxine+Others Systemic Vitavax 75 WP 2.0 kg/t
Mankozeb Contact Vondozeb Plus 1.0 kg/t