structure(list(Collection = structure(c(1L, 1L, 1L, 1L, 1L, 2L
), .Label = c("1", "2"), class = "factor"), Irrigation = structure(c(1L,
2L, 3L, 4L, 5L, 1L), .Label = c("Rate1", "Rate2", "Rate3", "Rate4",
"Rate5"), class = "factor"), meanSuc = c(0.585416666666667, 0.5032,
0.61375, 0.602775, 0.688466666666667, 0.545133333333333)), row.names =
 c(NA,
-6L), groups = structure(list(Collection = structure(1:2, .Label = c("1",
"2"), class = "factor"), .rows = list(1:5, 6L)), row.names = c(NA,
-2L), class = c("tbl_df", "tbl", "data.frame"), .drop = TRUE), class =
c("grouped_df",
"tbl_df", "tbl", "data.frame"))

Tukey_data <- dataAvgSucCI %>%
  mutate(Tukey_ID = paste(Collection, Irrigation, sep="_"))
TukeyAov <- aov(meanSuc ~ Tukey_ID,Tukey_data)
HSD.test(TukeyAov, "Tukey_ID", group=TRUE)