Foliar Treatments of 2,4-Dichlorophenoxyacetic Acid for Control of Common Scab in Potato Have Beneficial Effects on Powdery Scab Control

Table 3

Field trial number 2: effect of foliar applications of 100 or 400 mg/L 2,4-D on the foliage of Russet Burbank plants on powdery scab and common scab severity.

2,4-D rate; (mg/L)	Least square mean of disease cover score^a
	Powdery scab	Common scab
0	1.50	1.18^a
100	0.87	0.47^b
400	0.98	0.40^b
Rate	(𝐹(2,6) = 3.93, 𝑃=0.081)	(𝐹(2,6) = 7.58, 𝑃=0.023)

aDisease cover score (0–6 scale [12]) assesses surface area of tubers covered with lesions. Percentage cover is the estimated percentage of tuber surface coverage derived from the disease cover score.
Treatment least square means with the same letter within individual disease columns are not significantly different at 𝑃=0.025 using the Tukey adjusted pairwise test.