Category Archives: Carrot

Insect Pest and Crop Degree Day Update – June 13, 2017

Insect Degree Days

Weather Station Location Onion Maggot Seedcorn Maggot Cabbage Maggot Carrot Weevil Carrot Rust Fly Aster Leafhopper
(base 4°C) (base 4°C) (base 6°C) (base 7°C) (base 3°C) (base 9°C)
Harrow 716 716 556 481 800 351
Ridgetown 629 629 474 407 712 290
Delhi 618 618 464 399 700 284
Goderich 500 500 365 305 573 215
Guelph 463 463 332 274 538 182
Bradford* 523 523 388 329 593 227
Kemptville 502 502 381 326 571 232
Sudbury 353 353 257 216 412 147

*Bradford weather, degree day data and information courtesy of the University of Guelph – Muck Crops Research Station

Summary

Onion maggot flies are active in most areas of the province.

Cabbage maggot has reached the DD threshold for emergence in all areas of the province except up North.

The 2nd generation of seedcorn maggot flies have reached the DD threshold for emergence in Harrow. In most other areas of the province, we are just getting over the 1st generation or are currently between generations.

Carrot weevil adults are currently laying eggs, if they are present. In Harrow we have past the degree day threshold for 90% oviposition. This means if carrot weevils are present then almost all of the egg-laying has been completed.

The 1st generation of carrot rust fly is emerging or has emerged in the province.

All areas of the province have reached the DD threshold for overwintering Aster Leafhopper eggs to hatch. Harrow is nearing adult emergence of the local population of Aster Leafhopper adults.

IPM Update

Onion: Earliest direct seeded onions are at the fifth leaf stage while the majority are the third leaf stage. There is a low risk for Botrytis leaf blight. When scouting, check the underside of the outer leaves and look for small, light green to yellow lesions surrounded by white halos. Herbicide injury will be often more white than green but can be mistaken for Botrytis leaf blight. Thrips have been detected in most onion growing areas; pull the leaves apart and look down into the leaf base for 2mm-long grey adults or very small yellow nymphs ~1mm in length. Onion fields next to hay or overwintering rye are at a greater risk as thrips move once the hay or rye is cut.

Garlic: Continue to scout for symptoms of rot in the basal plate which may be due to bulb and stem nematode, Fusarium basal rot or white rot. Look for plants that have yellowing of foliage or tip dieback and dig carefully around the plant and look for fungal growth or rot on the stem. Onion thrips and onion maggot flies have been detected.

Brassica: First generation of cabbage maggots are active. Continue to scout for diamondback moth, cabbageworm, aphids, thrips and tarnished plant bugs. 

Celery: Scout for tarnished plant bugs as they are emerging and are typical found first around field borders.

 

Ontario DD Map June 11 2017

 

Below are the various insect DD thresholds for reference.

Thresholds

Use these thresholds as a guide, always confirm insect activity with actual field scouting and trap counts.

Degree Days
1st generation 2nd generation 3rd generation
Onion Maggot 210 1025 1772
Seedcorn Maggot 200 600 1000
Cabbage Maggot 314-398 847-960 1446-1604
Carrot Rust Fly 329 – 395 1399-1711 n/a
Carrot Weevil 138 – 156 Egg laying (oviposition) begins
455 90% of the egg-laying (oviposition) is complete
Aster Leafhopper 128 Overwintering eggs hatch
390 Local adult emergence

 

Insect Pest and Crop Degree Day Update – June 5, 2017

Ontario DD Map June 4Insect Degree Days

Weather Station Location Onion Maggot Seedcorn Maggot Cabbage Maggot Carrot Weevil Carrot Rust Fly Aster Leafhopper
(base 4°C) (base 4°C) (base 6°C) (base 7°C) (base 3°C) (base 9°C)
Harrow 613 613 467 400 690 283
Ridgetown 534 534 394 333 611 231
Delhi 519 519 380 321 593 220
Goderich 414 414 292 239 479 164
Guelph 396 396 278 227 463 149
Bradford*  438 438  318 266  501  178
Kemptville 409 409 302 254 471 175
Sudbury 261 261 179 146 314 91

Summary and IPM Update

Onion thrips have been seen on transplants in the Grand Bend area but at this point numbers are low.

Onion maggot flies have emerged and are active in most areas of the province. Current trap counts are low in the Holland Marsh area* and low to moderate in the Grand Bend area.

Cabbage maggot has reached the DD threshold for emergence in Harrow, Ridgetown, Delhi and Bradford. It is nearing the DD threshold in Goderich, Guelph and Kemptville.

The 2nd generation of seedcorn maggot flies have reached the DD threshold for emergence in Harrow. In most other areas of the province, we are just getting over the 1st generation or are currently between generations.

Carrot weevil adults are currently laying eggs, if they are present.

The 1st generation of carrot rust fly has begun to emerge in almost all areas of the province.

Most of the province (Ridgetown, Delhi, Goderich, Guelph, Bradford, Kemptville) have reached the DD threshold for overwintering Aster leafhopper eggs to hatch. Harrow is nearing adult emergence of the local population of Aster Leafhopper adults. Continue reading Insect Pest and Crop Degree Day Update – June 5, 2017

Insect Pest and Crop Degree Day Update – May 26

Ontario DD Map May 25

Insect Degree Days

 

Weather Station Location Onion Maggot Seedcorn Maggot Cabbage Maggot Carrot Weevil Carrot Rust Fly Aster Leafhopper
(base 4°C) (base 4°C) (base 6°C) (base 7°C) (base 3°C) (base 9°C)
Harrow 468 468 342 285 535 189
Ridgetown 408 408 288 237 475 155
Delhi 391 391 271 222 455 141
Goderich 308 308 206 164 363 108
Guelph 284 284 186 145 342 87
Bradford*  318 318   205 172  369  112
Kemptville 304 304 217 179 356 119
Sudbury 168 168 105 82 210 47

 

Continue reading Insect Pest and Crop Degree Day Update – May 26

Carrot Weevil Control Update

Carrot weevil remains the most important insect pest to many Ontario carrot growers, and the amount of damage seems to be increasing in recent years. Carrot weevil females overwinter in the soil and plant debris and lay their eggs in cavities in the crown of the carrots. These eggs develop and hatch into larvae and begin to feed on the carrot root. Feeding damage from the carrot weevil larvae causes unmarketable tunneling near the crown of the carrot and can account for significant losses to commercial growers.

Continue reading Carrot Weevil Control Update

66th Annual Muck Vegetable Growers Conference

The 66th Annual Muck Vegetable Growers Conference will be held April 12-13 at the Bradford and District Memorial Community located at 125 Simcoe St., Bradford, ON. The conference is free and registration starts at 8:30. For more details please see:  http://www.uoguelph.ca/muckcrop/muckconference.html

Continue reading 66th Annual Muck Vegetable Growers Conference

Flea Beetle Feeding Damage Found on Carrots in Ontario

Dennis Van Dyk, OMAFRA, Guelph; Manju Chandran and Mary Ruth McDonald, University of Guelph, Muck Crops Research Station.

For the first time in Ontario, feeding damage caused by flea beetle larvae has been confirmed in a commercial carrot field. The damage is characterized by irregularly shaped cavities along the length of the taproot (Figure 1). A trail of smaller feeding sites can sometimes be seen travelling down the length of the carrot (Figure 2).

flea beetle feeding
Figure 1. Large amounts feeding damage caused by flea beetle larvae

Continue reading Flea Beetle Feeding Damage Found on Carrots in Ontario