DD293482A5 - METHOD OF CONTROLLING RHIZOCTONIA SOLANI KROWN ON POTATO PLANTS WITH BACILLES - Google Patents

Abstract

The invention relates to the control of phytopathogenic pathogens by means of Bacillus pumilus or B.subtilis. The method according to the invention involves the use of microbial antagonists of the genus Bacillus for the treatment of seed potatoes. The reduction of the disease infestation in vascular and field experiments is demonstrated. {Bacillus subtilis; B. pumilus; phytopathogenic pathogens; Rhizoctonia solani; Potato plants; Infestation reduction}

Description

Characteristic of the known state of the art

The fight against Rhizoctonia solan! On potato plants, in addition to the usual cultivation measures, by the use of synthetically produced fungicides, by the großtonnagige application resistance and phytotoxic problems can be caused. In addition, fungicides are harmful to the environment, as they are usually degraded in the soil or in the plant not residue or only slowly.

As an alternative to the chemical control measures of phytopathogenic soil fungi, biological methods using microbial antagonists are increasingly being used in recent times. Thus, for example, for controlling Alternaria on cabbage, DE-OS 331171, Botrytis on strawberries, Fusarium on cucumbers or common larks, Pyrenochaeta on tomatoes, various soil fungi on cotton and sugar beets or Gaeumannomyces on cereals, see WP-DD 250456, WP-DD 264940 , WP-DD 270653, EP-PS 0276132, US-PS 4663512 and US-PS 4724147.

No information is available on the use of antagonistic forms of application in agricultural practice for the control of Rhizoctonia solani KÜHN in potato plants. The sensitivity of Rhizoctonia solani to the metabolic products of some antagonistic bacteria has only been demonstrated in in vitro studies EP.PS 0263502.

Applications of the fungus Verticillium biguttatum to control Rhizoctonia solani on plant potatoes during storage JAGER and VELVIS (1988), Netherl. J. Plant Pathol.94,225-231. At temperatures of at least 15 ^° C., application of conidia mycelial suspensions of this fungal antagonist causes a reduction in Rhizoctonia sclerotia formation on the surface of the potato tubers. For biological control measures, however, this method is only conditionally applicable because at temperatures below 15 ⁰ C, the antagonistic activities of Mykoparasiten be greatly reduced. Thus, in the usual storage conditions of 4-6 ⁰ C no control successes are expected.

Object of the invention

The object of the invention is to find microorganisms which are able to effectively protect plants ecologically from phytopathogenic pests.

Explanation of the essence of the invention

The invention has for its object to perform with antagonistic bacterial strains of the genus Bacillus effective control phytopathogenic pathogens.

It has been found that Bacillus pumilus Bp91 IMET11435, B.subtilis 6 / 86IMET11434 and B. subtilis Z11MET11327 as microbial antagonists in vitro cause strong inhibition of phytopathogenic pathogens (biomaltar agar, WAKSMAN agar, potato dextrose agar).

Description of the trunks:

1. Bacillus pumilus Bp91

The parent strain Bacillus Bp91 has been identified as Bacillus pumilus by the procedure of BERGEY'S Manual of Systematics Bacteriology, Vol. 2 (1986). The strain designation is Bacillus pumilus Bp.91. The belonging of the strain Bacillus pumilus Bp.91 to the species Bacillus pumilus was also detected serodiagnostic in the fluorescence antibody test with antisporensemm of the type strain Bacillus pumilus ATCC 7061. The strain B. pumilus differs from the type strain by high inhibitory activity against Fusarium oxysporum dianthi. The inhibition zone width in the streak test (FILIPPI et al., Plant and Soil 80 [1984], 119-125) is 18-20 mm for the strain B.pumilus Bp91 and only 4-5 mm for the type strain B. pumilus ATCC 7061. Strain B. pumilus Bp91 was isolated from a soil sample.

2. Bacillus subtilis 6/86

The starting strain Bacillus 6/86 was identified as Bacillus subtilis according to BERGEY'S Manual of Systematics Bacteriology, Vol. 2 (1986). The strain name is Bacillus subtilis 6/86. The membership of the strain B.subtilis 6/86 to the species Bacillus subtilis was serodiagnostic in the fluorescence antibody test with antisporensum of the type strain Bacillus subtilis ATCC 6051 detected. The strain B.subtilis 6/86 differs from the type strain by its high inhibitory activity against Fusarium oxysporum dianthi. The inhibition zone width in the Stichting test (FILIPPI et al, 1984) is approximately 18 mm for the B. subtilis strain 6/86 and only 5 to 6 mm for the B. subtilis ATCC 6051 strain. The strain B. subtilis 6/86 was obtained from a soil sample.

3. Bacillus subtilis 21

The parent strain Bacillus Z1 was identified as Bacillus subtilis according to BERGEY'S Manual of Systematics Bacteriology, Vol.2 (1986). The strain name is Bacillus subtilis Z1. The affiliation of the strain B. subtilis Z1 to the species Bacillus subtilis was serodiagnostic in the fluorescence antibody test with antisporensum of the type strain Bacillus subtilis

ATCC 6051 detected. The B.subtilis Z1 strain differs from the type strain in its high inhibitory activity

against Fusarium oxysporum dianthi. The inhibition zone width in the Stichting test (FILIPPI et al., 1984) for B. subtilis Z1 is 18 to 20 mm for the type strain B. subtilis ATCC 6051 at 5 to 6 mm. The B.subtilis Z1 strain was isolated from a soil sample.

The antagonist strains Bacillus pumilus Bp91, Bacillus subtilis 6/86 and B. subtilis Z1 are central Depository at the Central Institute for Microbiology and Experimental Therapy in Jena under the numbers IMET 11327, IMET11434 and IMET11435 deposited.

The use of the different microwave antagonists for the treatment of plant potatoes by application of culture solutions of the antagonists before planting at a concentration of the antagonist suspension of 10 ⁷ to 10 * germs / ml yielded significantly lower infestation indices of the treated plants compared to the untreated

Rhizoctonia infected controls. Thus, with these microwave antagonists in a Pflanzgutvorbehandlung in the

Partial protection against the harmful fungus Rhizoctonia solani possible. Due to the minor damage to the underground parts of plants of potato plants, an additional yield can be realized.

Auführungsbefsplele

example 1

To combat Rhizoctonia disease on potato plants, plant potatoes with natural Rhizoctonia infestation were immersed for 30 minutes in culture solutions of the Bacillus subtilis strains 6/86, Z1 or B.pumilus strain Bp91, then dried and planted in planters. In addition, soil applications were carried out with the antagonist suspensions. The plant pots were set up in the field. After a three - month vaginalization period of the potato plants, the Rhizoctonia infestation was detected.

application Disease index (in%) () ... 100 (100 = total infestation) Tuber yield per plant (in grams) 1988 untreated control 70.4 175 Bacillus pumilus Bp91 Bacillus subtilis 6/86 Bacillus subtilis Z1 36.6 27.1 30.1 250 230 245 1989 untreated control 55.2 190 Bacillus bacillus Bp91 Bacillus subtilis 6/86 Bacillus subtilis Z1 33.9 26.0 24.9 275 235 265

Example 2

To control Rhizoctonia disease on potato plants, plant potatoes with natural Rhizoctonia infestation were dipped for 30 minutes in culture solutions of Bacillus subtilis strains 6/86, Z1 and Bacillusumus strain Bp91 respectively, then dried and planted in the field 14 days later. At the end of the growing season of the potato plants the Rhizoctonia disease infestation was determined.

application Number of healthy plants (in%) Disease index (in%) 0 ... 100 (100 = total infestation) Tuber yield per plant (in grams) 1988 untreated control 0 45.6 910 Bacillus pumilus Bp91 Bacillus subtilis 6/86 Bacillus subtilis Z1 45 55 45 10.9 10.1 8.1 1090 1090 1270 1989 untreated control 0 46.7 1200 Bacillus pumilus Bp91 Bacillus subtilis 6/86 Bacillus subtilisZ! 70 75 70 6.3 6.1 6.6 1400 1400 1400

Claims (1)

Microorganisms for controlling phytopathogenic pathogens, characterized in that the bacterial strains Bacillus pumilus Bp91 IMET 11435, Bacillus subtilis 6 / 86IMET 11434 or B.subtilis Z1IMET11327 are used. field of use The invention relates to microorganisms for controlling phytopathogenic pests on potato plants in agriculture.