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level: Alfalfa pests

Questions and Answers List

level questions: Alfalfa pests

Question	Answer
What kind of alfalfa pest is this?	Alfalfa weevil
Alfalfa weevil eggs hatch in _ in S Iowa, and _ in N Iowa	Late April, early-to-mid May
How long does it take alfalfa weevil larvae to develop?	4 weeks
Adult alfalfa weevils feed on alfalfa and enter _ dormancy in sheltered sites along ditches, fencerows, and field borders.	Summer
Alfalfa weevils return to alfalfa fields in the _ where they mate. They overwinter as _ in the soil.	fall, adults.
Alfalfa weevil larvae feed on _ and _	Terminals and upper leaves
New alfalfa weevil adults remove _ after _	Shoot growth, 1st cutting
Start scouting for alfalfa weevil S of I-80 when _ GDDs have accumulated (base temperature _)	200 GDDs, 48°F
Start scouting for alfalfa weevil N of I-80 when _ GDDs have accumulated (base temperature _)	250, 48°F
True or False: Thresholds for alfalfa weevil management are calculated based on crop height, value, control costs, and growing conditions.	True
True or false: Tolerant alfalfa varieties exist for potato leaf hopper, but 1st year alfalfa of this sort must be carefully scouted even if it is a tolerant variety.	True
Alfalfa weevil management, True or false: If hay is near harvestable maturity, harvest the 1st cutting. Look for greenup; if greenup does not occur within 3-5 days, spray the stubble with an insecticide.	True
Alfalfa weevil management, True or false: Treat fields if they cannot be harvested within 5-7 days, but DO NOT treat flowering fields due to honeybee toxicity.	True.
What is this pest?	Potato leafhopper
How many generations do leaf hoppers have in Iowa?	2-3
What is hopperburn?	Potato leafhoppers inject a toxic substance into the plants that yellow the leaves. Resembles a v-shape.
What cuttings are most affected by potato leafhoppers?	2nd and 3rd cuttings, hit hardest in hot/dry weather.
True or false: Hard, driving rains drive potato leafhoppers off the leaves	True
When to scout for potato leafhoppers?	Scout once a week on 2nd and 3rd cutting hay from June-August.
What are potato leafhopper ETs based on?	Alfalfa type (Resistant or not), alfalfa height, avg number of leafhoppers per 10 sweeps
True or false: Potato leafhopper-resistant varieties of alfalfa still need monitoring when stands are very young	True
Potato leafhopper management, True or false: Lowest recommend insecticide rates work, but higher rates are needed when alfalfa is short	True
Potato leafhopper management, True or false: Harvest stunted plants that are yellowing, and treat the regrowth	True