b'Andys Advice:Zidua, A NewHerbicide for Weed Control in Potatoes By Andy Robinson, Extension Potato Agronomist, NDSU/UMNweed,amongothers),nightshade we were not able to see large differ-species, and selective grasses such as ences between treatments on weedbarnyardgrass,foxtailspeciesand control. However, other researcherscrabgrass. have demonstrated the effectivenessofZiduaandtankcombinations.Ziduaislesswatersolublethan We found that Zidua had good cropOutlook and Dual. This means more safetywhenitwasappliedtothewater is needed to activate this com- soil while potato stems were at leastpound,butitwillalsostayactive 3inchesunderthesoilsurfacelongercomparedtootherherbi- (Table 1 and Figure 1). cides.Theadvantageofalowerwater solubility is longer weed con- Insummary,cropinjuryfromthetrolbecauseitstaysactivelonger. useofZiduawasnotsignificant.One downside to this is that if not From other research conducted onenough water is available to activate Ziduaweknowthattank-mixingtheherbicide,weedseedscould additionalherbicideswillimproveIt is always a good day when a new emerge and not be controlled. Zidua weed control. This is a good addi-chemical is approved for weed con- is not a stand-alone herbicide and it tion to the weed control toolbox fortrol in potato production. I say this, shouldbetankmixedwithother those looking for improved pigweedbecause we do not have many com- herbicidesofdifferentmodesof or nightshade control options andpaniesdevelopingortestingnew action to improve weed control and for those who desire longer activityherbicidesforpotato.Wehad preventherbicide-resistance.Our frompreemergentherbicidepro-research plots in 2017 and 2018 to research had low weed pressure, so gram. determineZiduascropsafetyandeffectivenessatcontrollingweeds.Recently,BASFregisteredZidua(active ingredient is pyroxasulfone)for use in potato. Last year was thefirst year we saw Zidua use in com-mercial potato farms. A little background on Zidua. Thiscompound works similar to Outlookand Dual in that it disrupts cell divi-sionofweedseedthatarebegin-ning to grow or prior to emergingfrom the soil. These compounds areabsorbedbytheemergingshootsand roots. Ziduas strengths are oncontrolling pigweed species (includ-ingwaterhempandredrootpig-12 POTATO GROWER FEBRUARY 2021'