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Extension Entomology

Tag: efficacy trial

Sugarcane Aphids

–by Dr. Jeff Whitworth, Dr. Holly Schwarting and JR Ewing

Sugarcane aphids were still active in north central KS on 23 and 27 October, as were the beneficials (see pics).  Fields were being harvested and getting acceptable yields (growers reported 80 to 160 bu/acre, which they said was usual for the fields involved) without much interference caused by the stickiness of the honeydew (and it is sticky).

SCA Oct_leaf

 

SCA oct head

 

beneficials - aphids

Below are the results of sugarcane aphid efficacy trials conducted in Saline Co.  Aphid populations were, in our opinion, ideal for conducting trials of this nature because there were enough aphids to show any differences caused by the treatments, but not so many that the plants were overwhelmed or that the grower sprayed the field (thereby over-spraying these plots).

SCA efficacy trial 1

 

Means within a column followed by the same letter are not significantly different (P>0.05; PROC ANOVA; Mean comparison by LSD [SAS Institute 2003]).

SCA efficacy trial 2

 

Means within a column followed by the same letter are not significantly different (P>0.05; PROC ANOVA; Mean comparison by LSD [SAS Institute 2003]).

Alfalfa – Weevils and Aphids

—by Dr. Jeff Whitworth and Dr. Holly Schwarting

Alfalfa weevils continue to be very active in north central Kansas. The recent cooler weather has slowed down development a little but they are still feeding. We determined development from larvae collected on 20 and 22 April. Here is what the population breakdown looks like:

20 AprilNo. larvae   23 April No. larvae
12 1st Instars 4
25 2nd Instars 16
15 3rd Instars 30
   numerous Pupae numerous

alfalfa weevil

So what does this mean? Alfalfa weevil larval feeding will continue for another 7-10 days, depending on the weather. Egg hatch and consequent larval feeding has been going on since 13 March in north central KS. Insecticides applied since that time have provided adequate protection, for the most part.

field trial

This photo shows KSU chemical efficacy trials with many different products being tested, and the obvious untreated plots plus the border around the plots. The rest of the field was treated with Stallion® by MKC in Abilene, KS and, as illustrated here seemed to work relatively well with 1 application. Remember, feeding will continue for at least another week and therefore treatment (or re-treatment) may still be appropriate.

Alfalfa aphids, mainly pea aphids, are becoming more numerous throughout north central Kansas. Treating for alfalfa weevils probably pretty much decimated the natural enemies/beneficials and they will not repopulate as quickly as the aphids migrate in to infest fields.

 

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