Efficacy of new-generation acaricides in controlling mites in apple ...

Treatment
Rate (kg/ha)
EFFICACY OF NEW-GENERATION ACARICIDES
RESULTS AND DISCUSSION
Table 2. Effectiveness of Envidor 240 SC and Milbeknock EC in controlling mites on apple trees (2003–
2004)
Mean no. of mites per leaf
Weeks after treatment
2 4 6 8
Location E – Wilcze Piêtki, near Grójec, spraying date 4 June 2003
Milbeknock EC -0.75 l 0.0* 0.1 ab 0.1 ab 0.1 ab 3.2 ab
Milbeknock EC - 1.0 l 0.0 a 0.05 a 0.0 a 0.02 a 2.6 a
Ortus 05 SC - 1.0 l 0.0 a 0.1 ab 0.0 a 0.0 a 1.2 a
Control 1.7 b 2.8 c 3.8 c 7.0 c 100.0 c
Location F – Lewiczyn, near Grójec, spraying date 27 April 2004
Envidor 240 SC - 0.3 l 0.0 a 0.0 a 0.0 a 0.02 a 0.02 a
Envidor 240 SC - 0.4 l 0.0 a 0.0 a 0.0 a 0.0 a 0.0 a
Milbeknock EC - 0.75 l 0.0 a 0.02 a 0.0 a 1.3 b 0.8 a
Milbeknock EC - 1.0 l 0.0 a 0.05 a 0.0 a 0.2 a 0.2 a
Mitac 200 EC - 3.0 l 0.0 a 1.4 b 1.1 b 21.0 c 12.6 a
Control 4.1 b 25.1 c 8.1 c 18.3 c 100.0 b
Location G – Pêsy, near P³oñsk, spraying date 28 April 2004
Envidor 240 SC - 0.3 l 0.3 b 0.2 b 0.1 a 5.2 cd 13.3 b
Envidor 240 SC - 0.4 l 0.1 ab 0.9 c 0.1 a 0.6 b 6.4 ab
Milbeknock EC - 0.75 l 0.0 a 0.0 a 0.0 a 0.1 b 0.2 a
Milbeknock EC - 1.0 l 0.0 a 0.0 a 0.0 a 0.0 a 0.0 a
Mitac 200 EC - 3.0 l 0.0 a 0.02 a 0.02 a 0.0 a 0.3 a
Control 5.7 b 7.9 c 5.9 b 18.2 d 100.0 b
CII – cumulative index of infestation (control = 100%)
* Means followed by the same letter within columns do not differ significantly at P=0.05
CII
(%)
349
The acaricides Envidor 240 SC and Milbeknock EC in all experiments was very
effective on apple (Tables 1, 2) and plum tress (Table 3). The mite population on
apple leaves sprayed with this acaricide remained below the economical threshold
level (3 active stages of mites per leaf in the spring, and 5-7 mites per leaf in the
summer) during 8–12 weeks after treatment. A similar effect was obtained with the
tested standard acaricides. At locations A and B (Table 1) on trees treated with Envidor
240 SC and Milbeknock EC as well as with Omite 30 WP as the standard
product, the density of spider mites was low during the whole observation period
(until 11–12 weeks after the treatment). At location D (Table 1) as well as at location
E (Table 2), no spider mites were recorded during 7-8 weeks after treatment with
Milbeknock EC (0.75 l/ha and 1 l/ha) and the standard Ortus 05 SC. At location C
an application of Milbeknock EC resulted in a very low density of the spider mite
population during the following 7–8 weeks of observation, while the standard Ortus
05 SC showed a somewhat shorter activity period (6 weeks). The products Envidor
240 EC and Milbeknock EC applied at location F kept the density of spider mites at
a low level during 8 subsequent weeks of observation. The standard product Mitac
200 EC showed a good activity during 6 weeks after the treatment. However, 2 weeks
later the densities of spider mites were high and comparable to the control. At location
F the activity of Envidor 240 EC at a dose of 0.4 l/ha and Milbeknock EC on all