In 2019 the sugar beet trial was located in the fields of Nordic Beet Research (NBR) on the island Lolland close to Holeby. NBR is the industry’s research and development company founded by the sugar beet growers and the sugar industry in Denmark and Sweden. They contribute to a better beet production through experimental work, innovation and dissemination and demonstration. NBR bridges between research and other stakeholders. The National cluster in Denmark in WP 4 was assembled in June to discuss the 2019 trials. Participants from AU, SEGES, FRDK and NBR were present.
Table 1: Four IWM alternatives to conventional broad sprayed strategies.
Figure 1: photos of the strategies in June 2019. Strategy 1-4 with conventional sugar beet varieties and strategy 5 with ALS-tolerant variety. Generally, there was an uneven emergence of beets in the trial field.
The strategies concentrated on band spraying strategies as this is considered the most relevant IWM alternative to conventional broadcast-sprayed strategies (table 1 and figure 1). The trial was established as a demonstration trial in long strips across a field. Two replications were established. The strips had an untreated band running across the strategies established.
The biomass sampling in June 2019 showed that crop biomass in strategy 3 with a low dose rate as band spraying combined with three weed hoeings was in the higher end regarding fresh weight of sugarbeets compared to all other strategies (figure 2). However, weeds were best controlled in the standard strategy and the ALS-tolerant variety. The band of strategy 5 is 37.5 cm, which is much wider than the band of the other band applications (15 cm). The herbicide application rate in the row of the ALS-tolerant sugarbeets is the label rate, which will be realistic for a Danish authorisation (not currently authorised as band application). No statistical test have been applied. The main weed species in standard strategy (strategy 1) and the ALS-tolerant variety (strategy 5) was Veronica sp.. This weed species was present in all strategies, but in strategy 2 (band spraying with 3 herbicide applications) Polygonum convolvulus was the dominant weed species. In strategy 3, veronica sp., Polygonum aviculare and Stellaria media was equally frequent. In strategy 4, Raphanus sativus var. oleiformis was most frequent followed by Veronica sp. This indicate that strategies had variable effect on weed species.
Figure 2: Fresh biomass of crop (A) and weed (B) in June in the five strategies. Standard (strategy 1), Band with dose rates equal to strategy 1 in band applied 3 times combined with inter-row hoeing 3 times (strategy 2), Band with dose rates equal to strategy 1 in band applied 2 times combined with inter-row hoeing 3 times (strategy 3) and a strategy equal to strategy 3 with one weed hoeing replaced with a finger weeder treatment (strategy 4), bandspraying in broader band with ALS-product strategy including inter-row hoeing 3 times (strategy 5). The strategies are further described in the table.
Yield was sampled in two replicates in two blocks and was lowest for strategy 4 and 5 with small differences among the other strategies. The differences observed in June for sugarbeet biomass and weed biomass were less pronounced at harvest. In June, the biomass of sugar beets in strategy 3 was higher than other strategies, but this difference was not evident at harvest. Comparison of strategy 2 and 3 showed that the third herbicide band application did not provide extra weed control and higher yield. The lower yield for the ALS tolerant sugar beets were expected and is commonly observed. The benefit of this variety is the possibility to use ALS-herbicides, which are cheap and efficient.
Figure 3: Yield achieved for the five strategies. Standard (strategy 1), Band with dose rates equal to strategy 1 in band applied 3 times combined with inter-row hoeing 3 times (strategy 2), Band with dose rates equal to strategy 1 in band applied 2 times combined with inter-row hoeing 3 times (strategy 3) and a strategy equal to strategy 3 with one weed hoeing replaced with a finger weeder treatment (strategy 4), bandspraying in broader band with ALS-product strategy including inter-row hoeing 3 times (strategy 5). The strategies are further described in the table.
The IWMPRAISE demonstration trial was presented at the “Sugar beet day” in June 2019 (figure 3,4). NBR hosts a field day every second year, where a variety of sugar beet trials is presented, not only weed trials. On this day, there was opportunity to see all the trials and talk to the project managers.
Figures 3 + 4 Pictures from the “Sugarbeet Day” in June 2019. Nordic Beet Research (NBR), www.nordicbeet.nu
A Danish version of this text has been published on the IWMPRAISE Danish cluster website