Alfalfa Seed

Alfalfa Seed Chalcid

Sue Blodgett

 

Alfalfa seed chalcid adult, left; larva, right

 

This tiny pest is a small, black wasp measuring about 1/12 of an inch in length.  Chalcids overwinter as a fully grown larva inside seed.  Larvae pupate in the spring, emerging as adults after about 14 days.  There may be 2-3 generations per year; however, mature larvae may survive for 2 years before pupating.  Eggs are deposited into the young developing seed.  Only one larva may develop within a single alfalfa seed. 

 

Plant damage occurs when larvae infest seed.  Chalcid infestations occur when seed is left in the field, or infested alfalfa seed from field margins or volunteer plants are not harvested. 

Controls

Chemicals are less effective because eggs, larva and pupa stages develop within seed, protected from insecticide application.  Late maturing fields usually develop heavier infestations. 

 

Cultural controls, especially field sanitation is the best approach to managing alfalfa seed chalcid;  practices such as harrowing or discing to bury chalcid infested seed 1 inch deep followed by irrigation are effective in preventing adults from emerging.  Infested seed should be cleaned and screening destroyed.  Destroy chaff and/or screenings.  Eliminate volunteer alfalfa plants growing near seed fields.

 

 

Insecticide

Lbs Active Ingredient per Acre (Fl oz. or oz. product)

Preharvest Interval, remarks

Proaxis

2.56 – 3.84

7 days for hay. 24 hr REI. Extremely Hazardous to Bees!  Do not apply to alfalfa in bloom. Do not apply more than 0.24 pt /A per cutting.  Do not apply more than 0.96 pt/A per season.  Advisable to move bees during application and allow 3 (low rate) or 5 (high rate) days before re-introduction of bees

Warrior 1ECR,1

2.56-3.84 oz

7 days for hay. 24 hr REI.  Extremely Hazardous to Bees!  Do not apply to alfalfa in bloom. Do not apply more than 0.24 pt /A per cutting.  Do not apply more than 0.96 pt/A per season.  Advisable to move bees during application and allow 3 (low rate) or 5 (high rate) days before re-introduction of bees

R Restricted Use Pesticide 1Labeled for chemigation 224c labels may be available, check  with State Dept of Agriculture 3Several formulations.

* Chemigation varies by formulation.  Please check label.

The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality.

 

 

Categories: Alfalfa Seed, Insects

 

Date: 11/17/2006