Biological Plant Protection for Canola

This activity seeks to replace the synthetic plant protection product of the cruciferous crop with a biological preparation that is just as effective in controlling fungal diseases and insects.

It is important to reduce pollution in the field that derives from synthetic pesticides besides the leaching of nutrients in the conditions of integrated agriculture. Also, pesticide residue in the soil damages useful organisms who would control both the pests and the pathogens. During spraying, the used pesticide may spread from the field away to the surroundings through air by dust formed from soil particles and by water. Moreover, excessive use of pesticides brings along the resistance capability of pests against plant protection products, which causes new preparations to be put to use. These problems have in turn caused the need to design new innovative and alternative pest control methods.

As part of the experiments, we have applied the following two biological preparations:

  • BotaniGard 22WP Beauveria bassiana
  • Met52 Metarrhizium anisopliae

The preparations we test contain spores of conventional soil microorganisms. As a result of their application to plants, the number of protective microorganisms fighting fungal diseases and/or insects increases. This creates unfavorable environment for the development of pathogens and infects pests with entomopathogens.

Honeybees, which carry biological powder preparations on flowers, are used as a novelty in the application of plant protection products to plants. The formulations contain various microorganisms, the effectiveness of which in controlling pests depends on environmental conditions such as temperature, humidity and sunshine.

In 2017, patch test was carried out at the test field of the Estonian University of Life Sciences, where a biological preparation was used to repel beetles. The number of flowers of  was evaluated on the test patches, which showed that it was somewhat higher on the test patches sprayed with the preparation. Beetles were also picked from the experimental field and fed with 100% material in lab setting, showing mortality 4-6 days after spraying compared to controls.

In 2018, additional testing was carried out at the experimental field of the Estonian University of Life Sciences. 20 test plots were built in a 2 ha summer swede rape field. The test plots were sprayed with water, and with standard: 1x, 2x, 5x and 10x, accordingly. The test patches with different treatment norms were arranged in random order to minimize the effects of microclimatic conditions or soil variability. Beetles were also handpicked from the test plots to assess their mortality. Among beetles harvested after spraying, mortality was observed in the laboratory from the sixth day after spraying.

In 2019, experiments were performed in insect-resistant pavilions established in the field to assess the infestation of beetle larvae as bees carry the preparation to plants. In order to ensure correct results, the effect of the formula was evaluated both in test plot experiments as well as in lab conditions.

The results of three years work indicate that the beetles are infected with the entomopathogenic fungus contained in the biological preparation. At the same time, it does not cause high enough mortality to prevent crop loss. The best effects of this preparation are seen in the long run, especially in organic farming, to help reduce the population of beetles in the area. 

  1. The mortality rate of the formula is too low or too slow to achieve effective pest control, but in the long run it helps to reduce the number of the next generation.
  2. Both preparations infect beetles, but the effect is too slow.
  3. Both preparations infect the larvae inhabited in the flowers of the crop.
  4. The number of larvae in the soil was reduced.
  5. Neither preparation is suitable for controlling beetles in the bud damage phase.
  6. These preparations could be used as a supportive method to reduce the oversized beetle population.
Effect on pollinators

No significant increase in mortality was observed in honeybees when exposed to flowers or filter paper containing the active substance BotaniGard, Beauveria bassiana. This is also confirmed by several scientific articles. When honeybees are used as inoculants, a method must be used to prevent the bees from passing through the powder container when entering the hive. The internal temperature of the hive is higher than necessary for the development of B. bassiana. When exposed to the formula, bees are not harmed significantly, as the hair covering the pollinator’s body prevents fungal spores from entering the bee’s cuticle and the bees’ habit of cleaning the body of pollen removes most of the fungal spores.

It is confirmed that the carry-over effect of the formula from the dispenser  to the beehive is unlikely as the bees lose most of the portable powder during the flight. All the ingredients of the powder are of natural origin (clay, B. bassiana) and B. bassiana is also a fungus found in natural habitants. Therefore, honey taken from hives is marketable.

Estonian University of Life Sciences – Reet Karise, Marika Mänd, Anne Must, Angela Ploomi, Egle Liiskmann