Determine the timing of postemergence insecticide applications by monitoring local flight activity of adult root maggots with orange-color sticky traps. Control is most effective when insecticide application coincides with the time of peak seasonal fly capture on traps; earlier and especially later application is less effective. Total seasonal captures of 40 to 50 flies per trap through peak collection justify postemergence treatments. See University of Idaho publication CIS 999, IPM Guide to Sugar Beet Root Maggot, for details. (See page i of this book for ordering information.)

Adult root maggot flies are highly mobile; they continually colonize fields over long distances during a 6-week egg-laying period. Control would require repeated insecticide applications to kill flies before they laid eggs, but this has the potential negative side effects of selecting for pesticide resistant strains and triggering outbreaks of aphids and leaf-feeding caterpillars by eliminating their natural enemies.

Larval control

1. aldicarb (Temik 15G, Temik 15G Lock’n Load) at 1.05 to 2.1 lb ai/a. PHI 90 days, 120 days if tops are fed to livestock. Do not use tops as food for humans. Do not make more than one at planting and two postemergence applications per crop. Do not exceed a total of 4.95 lb ai/a per season.

At planting (or within 1 week prior)—Drill granules 1 to 3 inches below seedline. Granules can be placed into the seed furrow if rate does not exceed 1.05 lb ai/a.

Postemergence—Apply granules to both sides of plant row and immediately work into the soil or cover with soil, or, for furrow irrigation side-dress granules 4 to 8 inches to water-furrow side of plant row and at furrow depth. Irrigate soon after application. Apply within 60 days after planting. Do not make any postemergence applications if 4.05 to 4.95 lb ai/a was applied at planting or within 1 week before planting.

2. carbofuran (Furadan 4F) at 2 lb ai/a postemergence. PHI 90 days. Apply in 4- to 5- inch band over row. Do not apply more than 2 lb ai/a per season. Time treatment so application begins after adult flies emerge. Moisture after treatment is needed to incorporate and activate carbofuran (rain is needed in furrow-irrigated fields; in sprinkler-irrigated fields, follow treatment with light irrigation). OR and ID 24(c).

3. chlorpyrifos (Lorsban 15G, Nufos 15G)

At planting—Apply at 1 to 2 lb ai/a based on 22-inch row spacing. Apply in 4- to 5- inch band behind planter shoe, over drill row, and in front of press wheel; do not apply granules in direct contact with seeds. Incorporate into top ¹⁄2 to 1 inch of soil. If heavy fly pressure is expected, you can augment at planting applications with Lorsban 4E postemergence.

Postemergence—Apply at 1.5 to 2 lb ai/a based on 22-inch row spacing. Apply granules in 3- to 5- inch band over row (up to 2 to 4 leaf stage). Incorporate into the top ¹⁄2 to 1 inch of soil.

Do not make more than one application per year.

4. chlorpyrifos (Lorsban 4E, Lorsban 75WG, and others

Postemergence (primary treatment)—Apply at 0.67 to 1 lb ai/a band application. Apply spray in 5- to 7- inch band over row, lightly incorporate mechanically or with irrigation. Base application timing on local monitoring of fly activity with traps. Apply from 7 days before until 3 days after peak adult emergence. Do not apply more than 2 lb ai/a of the 75WG formulation per season or more than 3 lb ai/a of the 4E formulation per season. Do not make more than three applications of Lorsban per season.

Postemergence (supplemental treatment following application of Lorsban 15G or Nufos 15G at planting)—Apply at either 1 lb ai/a broadcast or 0.335 to 0.67 lb ai/a band application.

Do not apply any treatment postemergence within 30 days of harvest of beet roots or tops; do not allow livestock to graze in treated areas or harvest treated beet tops as feed for livestock or dairy animals within 30 days of last treatment.

5. diazinon (Diazinon 14G) at 1 to 2 lb ai/a. Apply in a 5- to 7- inch band incorporated 2 to 3 inches at planting. Do not apply more than 4 lb ai/a to the soil per season.

6. diazinon (Diazinon 4E) at 3 to 4 lb ai/a. Broadcast just before planting and incorporate into soil 4 to 6 inches. Do not apply more than 4 lb ai/a to the soil per season. FIFRA 2(ee) recommendation for Idaho and Oregon only.

7. phorate
At planting (Phorate 20G, Thimet 20G)—Apply at 0.68 to 0.9 oz ai/1,000 row ft. PHI 30 days. Do not feed tops or silage to dairy cattle. Do not place granules in direct contact with seed. Drill to side of seed or band over seed. No more than one application per cropping season.

Postemergence (Thimet 20G)—Apply at 0.98 to 1.5 lb ai/a to foliage when plants are dry. Only one treatment postemergence per season. Do not feed tops or silage to dairy cattle. No more than one application per cropping season.

8. terbufos (Counter CR Lock’n Load, Counter 15G Lock’n Load). One application per year. Do not place in direct contact with seed. Do not exceed 2 lb ai/a.

At planting—Apply at 0.6 to 1.2 oz ai/1,000 row ft banded or modified in-furrow. Apply in 5- to 7- inch band over the row and lightly incorporate to 1 inch; or apply in furrow, 2 to 3 inches behind seed drop zone after some soil has covered the seed.

Postemergence—Apply at 0.6 to 1.2 oz ai/1,000 row ft banded. Apply in 5- to 7- inch band over the row; lightly incorporate. Apply at first sign of fly emergence.

9. zeta-cypermethrin (Mustang ) at planting application for suppression only of light to moderate infestations at 0.05 lb ai/a. Apply in furrow or in a 3 to 4 inch T-Band (band over open furrow) in a minimum of 3 to 5 gal water per acre. PHI 50 days. Do not apply more than 0.15 lb ai/a per season (at planting + foliar applications).

2. chlorpyrifos (Lorsban 4E, Lorsban 75WG, and others at 0.25 to 0.5 lb ai/a postemergence broadcast. PHI 30 days. Do not allow livestock to graze in treated areas or harvest treated beet tops as feed for meat or dairy animals within 30 days after last treatment. Controls adults present at time of applications.

3. chlorpyrifos (Chlorpyrifos 4E AG, Nufos 4E) at 0.5 lb ai/a postemergence in 7.5-inch band. PHI 30 days. Do not allow livestock to graze in treated areas or harvest treated beet tops as feed for meat or dairy animals within 30 days after last treatment. Controls adults present at time of applications.

4. naled (Dibrom 8 Emulsive) at 1 lb ai/a. PHI 2 days. Recommendation as permitted under FIFRA Section 2(ee). Do not apply more than 5 lb ai/a per season.

5. zeta-cypermethrin (Mustang) at 0.028 to 0.05 lb ai/a. PHI 50 days. Do not apply more than 0.15 lb ai/a per season (at planting + foliar applications). Apply with ground or air equipment using sufficient water to obtain full coverage of foliage.