Table 2.

Effectiveness ratings of biorational compounds against powdery mildew on lilac.

TreatmentWhole plant*Individual leaf*
1991
Bayleton 2 week interval1.0 c**1.1 c
Bayleton 4 week interval1.0 c1.1 c
M-Pede 2 week interval2.0 bc2.1 abcd
M-Pede 4 week interval1.1c1.6 bcd
SunSpray oil 2 week interval1.0 c1.0 d
SunSpray oil 4 week interval1.0 c1.0 d
Cloud Cover 4 week interval2.8 abc2.9 abc
Water control 2 week interval4.0 ab3.6 a
Water control 4 week interval4.1 a3.5 ab
1992
Bayleton1.0 b1.0 b
SunSpray + sodium bicarbonate1.2 b1.0 b
Saf-T-Side1.0 b1.0 b
SunSpray oil2.2 ab2.6 ab
M-Pede2.6 ab2.5 ab
Sodium bicarbonate3.7 a3.8 a
Water control4.0 a4.1 a

  • ↵* Disease ratings based on a 1 - 5 scale; 1=0 - 20%; 2 = 21 - 40%; 3 = 41 - 60%; 4 = 61 - 80%; 5 = 81 - 100% infection.

  • ↵** Means within columns and years with at least one letter in common are not significantly different.