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In the GUDP project IPMIROER, the effect of the insecticides Gaucho, Cruiser Force and Force is investigated in two trials in 2015 and 2017.
In two trials 2017, all of the insecticide seed treatments tested give a higher plant number at full emergence compared to untreated, and there is a tendency that for Gaucho 60 g gives the highest plant numbers. All insecticides have reduced attack of pygmy beetles with an average of 56 per cent infected plants in untreated. A yield increase of 4 per cent is indicated with Gaucho. In two trials 2015, attacks of pests have generally been weak. In one of the trials, there has been attack of soil pests, mainly millipeds, by 34 per cent in untreated and the seed treatments have reduced the attack. However, the attacks have not been severe enough to result in any yield increase.
In the trials 2015 and 2017, there has been no need for insecticide spraying, as the seed treatments have reduced the attack of soil borne pests. There have been only sporadic attacks of black aphids.
Earlier studies from 2006-2011 in 21 trials have shown that Gaucho 60 g in general result in a significant yield increase of 3 per cent compared to untreated. However, yield increase can be higher if attacks of pests are severe. In 2008, where there was a severe attack of black bean aphids (and special dry conditions at emergence), Gaucho showed a 19 per cent yield increase compared to untreated. In 2011, with severe attacks of thrips, a yield increase of 10 per cent with Gaucho was obtained compared to untreated.
In the GUDP project IPMIROER prevention of fungicide resistance in leaf diseases is investigated with two trials 2016-2017. Two varieties with different disease susceptibility have been used. The treatments include a variety of treatment strategies with a variety of active substances and mechanism of action as well as treatment times. It has been investigated whether the strategies can give the same or better effect on leaf diseases and yield potential in comparison to normal practice.
The results have indicated that different treatment strategies for prevention of fungicide resistance have reduced the leaf disease attacks and have resulted in yield increase compared to untreated. There have been no clear differences between the different strategies, but the results indicate that the need for leaf disease control depends on which leaf disease dominates and the particular disease pressure in that year.
In average of six trials four sprayings have controlled all weed and maximum yield is achieved. Tractor pulled hoeing in combination with four sprayings show a tendency to yield reduction until 3 percent. Hoeing has increased yield when weed is present where only one, two or three sprayings has been executed. In two trials one spraying has been sufficient to control the weed, but those trials are not representative.
Based on the present and earlier trial results a model to describe the relation between weed cover and relative sugar yield has been developed. The trial results show if more than 2 percent of the soil surface is covered by weed after maximum efficacy on weed is reached after finalised weed control or 2 percent of the canopy is covered by weed in august yield losses is likely to occur. This is an adaptation of previous thresholds.
The fourth spraying may be substituted by one or two mechanical hoeing’s still achieving maximum yield. This will reduce the Danish treatment index by 28 percent in the present trials. Further reduction may be achieved by using band spraying in combination with mechanical hoeing.
Trials in 2014 show a weak tendency to advantage of Spray Plus in humid conditions when almost moist occur on the leafs in the spraying situation. There is a tendency that improved coverage of the spray fan – nozzle F02-110 Hardi – on the weed leafs is more important in dry conditions while no difference is obtained in moist conditions.
Trials in 2016 and 2017 show mixing of the oil Renol S increase efficacy compared to none additive in the tankmix. Minidrift 02-110 Hardi nozzle show a tendence to reducere efficacy of the herbicides more than Low Drift 02-110 Hardi Nozzle that also reduce efficacy compared to flat fan Hardi nozzle 02-110. In this is an environmental conflict and compensating for an exchange to lowdrift or minidrift may demand an increase in dosage.
Increased supply of nitrogen will in general not replace a part of the herbicide dosage as an alternative. This corresponds to earlier trials indicating beets having a low ability to compete with the weed.
The general trend was a decreasing sowing quality with increased drilling speed. This affected in variable degree plant emergence, yield and harvest losses.