Surfactant effects on wettability of Penicillium frequentans formulations to improve brown rot biocontrol

Foliar application of three dithiocarbamates inhibits the absorption and accumulation of Cd in wheat

In cadmium (Cd) contaminated farmland soil, antagonism between elements can be used to control the absorption and accumulation of Cd in crops through the external application of zinc (Zn) and manganese (Mn). Dithiocarbamates (DTCs) are highly effective fungicides commonly used in farmlands, and DTCs are rich in Zn and Mn. We selected three representative DTCs (propineb, mancozeb, and zineb) for a field experiment in Henan province, China. The effects of DTC on Cd absorption and accumulation in wheat and the interaction of Zn, Mn, and Cd in wheat after spraying of DTC were studied using different application times at the heading stage. The results showed that after foliar spraying of DTCs according to pesticide application requirements, wheat yield was not affected. The Zn and Mn contents in grains increased, with the highest increases being 19.2% and 12.4%, respectively. Zn and Cd as well as Mn and Cd were antagonistic in wheat, and the transport of Cd from soil to root and from husk to grain was inhibited. The bioconcentration factor (grains/soil) decreased from 1.3 to 0.68 and the translocation factor (grains/husks) decreased from 0.76 to 0.35. The Cd content in grains decreased by 60.4%, 52.8%, and 25.6% with mancozeb, propineb, and zineb applications, respectively, and the Cd reduction effect of spraying DTCs twice was better than that of spraying DTCs once and thrice. The results show that DTCs application could reduce the Cd content in wheat grains and realize the dual effects of crop disease prevention and Cd reduction.

Balance between resilient fruit surface microbial community and population of Monilinia spp. after biopesticide field applications of Penicillium frequentans

The microbial variability on the host plant surface must be maintained because population diversity and quantity are essential to avoid disease development. It would be necessary to examine the patterns and mechanisms associated with the massive and reiterative introduction of a microbial pest control agent. The effect of inundative releases of biopesticide formulations containing Penicillium frequentans for the control of Monilinia spp. populations, and the effect on fruit surface microbiota on 18 stone fruit field experiments located in four European countries for more than two crop seasons against brown rot were studied. P. frequentans was monitored after application in order to assess whether it was persistent or not in the environment. Hydrolysis of fluorescein diacetate and denaturing gradient gel electrophoresis were used to study the effects of P. frequentans on fungal and bacterial non-target populations on fruit surface. The effect of P. frequentans formulations on the populations of Monilinia spp. on fruit was also assessed in different orchards. P. frequentans population on stone fruit surfaces showed ranged from 100 to 10,000 CFU cm^-2, and postharvest recovered populations were more than 10-100-fold higher than preharvest recovered populations. The population of P. frequentans varied among orchards and years, rather than by the type of formulation. P. frequentans formulation reduced Monilinia spp. population and brown rot and latent infections caused by this pathogen both before and at harvest, while stabilizing or increasing antagonist populations and avoiding non-target microorganisms. However, fungicides reduced significantly the microbial activity on nectarine surfaces.

Bacillus Methylotrophicus Has Potential Applications Against Monilinia Fructicola

Biocontrol is a cost-effective and environmentally friendly technique used in agricultural production. We isolated and screened a bacterial strain from the soils of a peach orchard with high yield. Using biochemical and physiological analysis as well as phylogenetic sequencing data, we identified a strain of Bacillus methylotrophicus, strain XJ-C. The results of our screening trials showed that XJ-C was able to suppress M. fructicola at an inhibition rate of 81.57%. Following the application of a 1×10⁹ CFU/mL XJ-C strain suspension to the fruits, leaves, and shoots of peach trees infected with M. fructicola, the inhibition rate reached 64.31%, 97.34%, and 64.28%, respectively. Using OM and SEM, we observed that, under the inhibition of strain XJ-C, M. fructicola mycelium and spores were abnormally shaped. Under TEM, cell walls were transparent, organelles had disappeared, and the intracellular vacuole was deformed. Thus, XJ-C has the potential to be used in biocontrol.

Dispersion, persistence, and stability of the biocontrol agent Penicillium frequentans strain 909 after stone fruit tree applications

The capacity of dispersion, persistence, and stability from biocontrol agents is essential before these organisms can be developed into a commercial product. Interactions that microorganisms establish with stone fruit trees may be beneficial in the exploitation of trees in agriculture as crop production. The natural background levels of Penicillium frequentans strain 909 dispersion, persistence, and stability were assessed after tree applications and postharvest conditions. A fingerprinting-based approach to trace genetic stability of P. frequentans along stored time and its release in the field was developed. P. frequentans was successfully traced and discriminated. This strain was dispersed well in treated trees, persisting in the ecosystem up to 2 weeks and staying genetically stable after 36 months of storage. However, the dispersal of P. frequentans was very limited on around untreated trees and soil. P. frequentans dispersed randomly into the air, and its presence reduced from the first day to disappear completely at 15-21 days after application. Great losses of P. frequentans and its increased dispersal in open field conditions probably resulted from rainfall. Biological control strategies with Pf909 were discussed.