Abstract: DSF-based microbial pathogens may be controlled by certain methods and compositions. A method of controlling diseases caused in a host organism by pathogenic microbial expression of ?,? unsaturated fatty acid signal (DSF) molecules involves inoculating the host organism with a non-pathogenic microbe that disrupts ?,? unsaturated fatty acid signal molecule-mediated cell-cell communication by the pathogenic microbe in the host organism. Microbes having protein expression that interferes with ?,? unsaturated fatty acid signal molecule-mediated cell-cell communication by the pathogenic microbe in the host organism can be identified and isolated or engineered by transformation with DSF-interference (inhibition or activation) gene or genes. Genes conferring DSF-interference activity can also be expressed in organisms (e.g., plants) susceptible to diseases caused by microbes that use DSF, resulting in genetically resistant organisms.

Abstract: DSF-based microbial pathogens may be controlled by certain methods and compositions. A method of controlling diseases caused in a host organism by pathogenic microbial expression of ?,? unsaturated fatty acid signal (DSF) molecules involves inoculating the host organism with a non-pathogenic microbe that disrupts ?,? unsaturated fatty acid signal molecule-mediated cell-cell communication by the pathogenic microbe in the host organism. Microbes having protein expression that interferes with ?,? unsaturated fatty acid signal molecule-mediated cell-cell communication by the pathogenic microbe in the host organism can be identified and isolated or engineered by transformation with DSF-interference (inhibition or activation) gene or genes. Genes conferring DSF-interference activity can also be expressed in organisms (e.g., plants) susceptible to diseases caused by microbes that use DSF, resulting in genetically resistant organisms.

Abstract: A method is provided of reducing fruit russetting by treating the surface of a fruit to reduce the amount of auxins present on the surface. In a preferred embodiment, the population of auxin-producing bacteria is reduced by providing a competing auxin-deficient bacterial population.

Abstract: Plant host acceptable microorganisms, which are ice nucleation deficient and use at least one nutrient from the plant also used by ice nucleating native microorganisms, are applied to a plant part at an early stage in the growth cycle. The multiplication of the native ice nucleating microorganisms is inhibited, so that under normal frost conditions encountered in the field, frost damage is substantially diminished. The non-nucleating microorganisms may be obtained by special selection procedures, selecting from naturally occuring microorganisms or mutagenized microorganisms, where additionally the organisms may be transformed to provide for other desirable properties.

Abstract: A novel pathovar has been isolated and purified, which pathovar most resembles Alternaria zinniae Pape, but has a host specificity for Italian thistle. By administering spores of this pathovar, called Alternaria sp., particularly shortly after emergence, Italian thistle growth is substantially inhibited.The spores of Alternaria sp. described in the subject invention have been deposited at the A.T.C.C. on Aug. 17, 1984 and given Accession No. 20723.

Abstract: DNA sequences encoding for ice nucleation activity are isolated and introduced into unicellular hosts. The modified hosts demonstrate ice nucleation activity analogous to the DNA source host. The cellular products find use in inhibiting supercooling.

Abstract: Plant host acceptable microorganisms, which are ice nucleation deficient and use at least one nutrient from the plant also used by ice nucleating native microorganisms, are applied to a plant part at an early stage in the growth cycle. The multiplication of the native ice nucleating microorganisms is inhibited, so that under normal frost conditions encountered in the field, frost damage is substantially diminished. The non-nucleating microorganisms may be obtained by special selection procedures, selecting from naturally occurring microorganisms or mutagenized microorganisms, where additionally the organisms may be transformed to provide for other desirable properties.The following organisms have been deposited at the A.T.C.C. on Aug. 13, 1981; A5-01, A5-05-1, A5-06, A5-10-1, A5-26, and A4-2B-10.

Abstract: The method for reducing the temperature at which freezing takes place in plants to reduce frost damage by the addition of non-ice nucleating bacteria to the plants prior to the onset of freezing temperature and preferably while the plants are in their seedling stage.

Abstract: The protection of plants against frost damage comprising treating the plants before the onset of freezing cold with bacterium M232A.