Preserving pollinators
It is essential to carry out spraying treatments outside the foraging periods of pollinators, especially bees (regulatory prohibition).
By foraging on all types of flowers, bees contribute to the pollination of crops and improve the quality of the harvest. For example, the presence of hives near rapeseed fields helps improve crop pollination and can increase yield by about 10%, depending on weather conditions.
During the flowering period (from the first flower of the stand to the last) and exudate secretion (aphid secretion), pollinators are particularly present and therefore vulnerable. Treatments (except derogations and always in the absence of insects) are thus prohibited.
Apple and Pear Trees
Outside the flowering period of the main species
The apple tree and pear tree do not intrinsically release exudates. For apple and pear trees, the grass cover between rows and orchard edges constitute potential risk sources. The grass cover consists of grasses that are not attractive to bees, but as the orchard ages, it can deteriorate and give way to other melliferous species (dandelion, clover, mallow, etc.). In case of flowering weeds within the inter-rows, it is recommended to cut the grass cover just before applying products to avoid treatments on flowering weeds. Hedges at the orchard edges play a role in limiting drift, preventing product transfer to adjacent areas.
Flowering and exudate secretion periods
The flowering period of apple and pear trees lasts about 3 weeks between the opening of the first flower and the petal fall of the last. In France, this flowering period generally occurs between late March (south) and mid-May (north). However, disparities exist depending on regions. You should observe your fields and adapt these recommendations to the actual conditions. The duration of this period also varies depending on the cultivated variety and climatic conditions. For example, poor weather conditions slow tree growth and thus lengthen the flowering period.
Flowering and exudate secretion periods
Rapeseed flowering occurs from stage F1 (50% of plants with a first flower open) to stage G3 (the first 10 siliques on the main stem measure more than 4 cm). At this stage, some flowers may still persist in the canopy. Rapeseed flowering usually takes place between March 15 and May 15. Generally, no exudates are observed on rapeseed.
Flowering and exudate secretion periods
The flowering period starts in June and ends in early August, depending on sowing date. It lasts about 3 weeks to 1 month. Exudate production is observed depending on aphid attacks.
Flowering periods of maize and sweet corn
In the absence of nectar production, only the pollen emission period of maize and sweet corn can be favorable to bee presence. This period starts from the opening of the first anthers and ends after the last anthers open. Depending on crops conditions, climatic conditions, and varieties (maize or sweet corn), the pollen release period lasts about 8 days.
Exudate secretion period
For maize, the main exudate to consider is honeydew, a sugary secretion produced by aphids in case of heavy infestation. These secretions may be present even after the crop's flowering period. Note that conditions favorable to aphid outbreaks and honeydew production are quite rare on maize and sweet corn.
Weeds can also attract bees
Weeds present in the field must also be considered even if the crop is not in flowering period.
Cereal Straw Crops
Flowering periods of cereal straw crops
Cereal straw crops are not frequented by bees during flowering (absence of nectar, no pollen collection from cereal straw crops by bees).
Exudate secretion periods
For cereal straw crops, the main exudate to consider is honeydew, a sugary secretion produced by aphids. The amount of honeydew is proportional to the aphid population level. The risk to consider concerns only aphid protection on ears.
As an indication, the amount of honeydew becomes significant when infestation exceeds about 40 aphids per ear.
Weeds can also attract bees
Flowering weeds present in the field must also be considered even if the crop is not attractive to bees.
Faba Beans
Flowering and exudate secretion periods
The flowering period of winter faba bean occurs in May and spring faba bean in June. Generally, no exudates are observed on faba bean.
Pea Protein Crops
Flowering and exudate secretion periods
Winter pea flowering occurs in May and spring pea from May 15 to June 15. Generally, no exudate secretion is observed on peas.
Flowering periods
Generally, potato flowering is observed during June. The flowering period is short and lasts only a few days. At the same time, many other species, notably melliferous, are in flower and more attractive to bees. Flowering is also a strong varietal characteristic. Indeed, some varieties produce few or no flowers.
Main source: https://www.syngenta.fr/agriculture-durable/bonnes-pratiques-agricoles/article/pollinisateurs-et-pulverisation
And
Good practices for treatment during flowering to protect bees / AGPM (2015)
