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The impact of cotton cultivar, plant growth regulator (PGR), and fungicide programs on the diseases target spot, areolate mildew, and hardlock, along with plant growth and yield variables, were assessed in 2017, 2018, and 2019. Deltapine 1646 B2XF [DP1646] was planted in all years; PhytoGen 490 W3FE replaced PhytoGen 499 WRF in 2018. Standard and aggressive PGR programs included two and three mepiquat chloride applications, respectively. Fungicide programs included a no-fungicide control, along with one or two applications of 147 g ai ha-1 fluxapyroxad + pyraclostrobin. Compared with the PhytoGen cultivars, DP1646 suffered less target spot-incited defoliation for the no-fungicide control and one- but not two-fungicide-application programs. Target spot defoliation was greatest in 2018 with no-fungicide control and the two-fungicide-application program having the greatest and lowest defoliation, respectively. In 2019, areolate mildew defoliation was greater for no-fungicide control than one- or two-fungicide-application programs. Hardlock incidence differed by year and cultivar but not PGR or fungicide program. PGR program impacted areolate mildew-incited defoliation, plant height, and lint content but not target spot-incited defoliation, hardlock incidence, open boll counts, yield, and loan value. Fungicide-related yield gains were noted for target spot-damaged PHY490 in 2018 and areolate mildew-damaged DP1646 in 2019. DP1646 had greater yield than either PhytoGen cultivar. Loan values, which differed only in 2017, were not impacted by PGR or fungicide program. Overall, cultivar and fungicide, but not PGR program significantly influenced disease-incited defoliation, growth parameters, yield, and loan value.
