VCR – Vegetable Crop Report – August 15th, 2024

Almost all counties continue to trend above their 10 year average GDD, with the exception of Thunder Bay which is on trend with its 10 year average.

Crop Updates

Brassica Crops – Transplanting for late broccoli has finished. Alternaria can cause head rot in broccoli and cauliflower if spores are able to infect the beads/curds and secondary bacteria are able to get established and cause rot. Conditions continue to be favourable for brassica downy mildew.

Garlic – Stained bulb wrappers due to Pseudomonas bacterial species are common this year (Figure 1). The increased incidence of these symptoms are likely due to a growing season with almost constant moisture, wet conditions at harvest and slower curing conditions in July/August 2023. To reduce incidence in 2025, rogue out cloves with staining and missing bulb wrappers and do not use them as planting stock. Avoid planting in poorly drained fields and plant in raised beds if there are concerns of flooding in a particular field. Avoid planting in headlands or areas that are in the shade as these areas often result in extended periods of leaf wetness which are more favourable for bacterial development. Avoid overhead irrigation and utilize drip tape instead. Always implement a 4-year crop rotation.

**Figure 1** – Brown streaking of *Pseudomonas cedrina* – Photo by R.A.G. 2024.

**Figure 2** – Decaying bulb wrappers of *Pseudomonas marginalis* – 2023.

**Figure 3** – Internal bulb rot of *Pseudomonas fluorescens* – 2024.

Onions – Early transplants continue to be harvested and direct seeded onions are starting to lodge. Stemphylium leaf blight and tipburn is starting to take hold in direct seeded fields. Royal MH can be applied for sprout control when 50% of the crop has lodged and there are green tops that are still present to absorb the product. Apply at least 10 days before the crop is harvested. Now is a great time to assess damage plots that were put up in the spring. Determining the number of plants that survived out of the 100 germinated/transplanted plants that were counted at the start of the season is valuable information to determine what percentage of plants died due to onion maggot.

Pest Degree Day Forecasting

County	Carrot Rust Fly	Onion Maggot	Carrot Weevil	Aster Leafhopper	Tarnished Plant Bug	Cabbage Maggot	Seedcorn Maggot	European Corn Borer
THRESHOLD	329-395, 1399-1711	210-700, 1025-1515	138-156, 455+	128+	40+	314-398, 847-960, 1446-1604	200-350, 600-750, 1000-1150	See legend below
Bruce***	1639	1496	1107	869	553	1231	1496	759
Chatham-Kent*	1980	1831	1415	1163	801	1548	1831	1039
Durham***	1858	1710	1302	1055	719	1432	1710	938
Essex*	2146	1992	1558	1294	920	1698	1992	1167
Huron***	1766	1620	1209	961	637	1341	1620	845
Kemptville***	1858	1712	1320	1079	746	1444	1712	964
Lambton**	1968	1821	1402	1147	798	1537	1821	1025
Middlesex**	1982	1832	1408	1151	798	1544	1832	1030
Norfolk**	1932	1781	1355	1102	752	1491	1781	981
Peterborough	1738	1593	1195	952	627	1323	1593	838
Renfrew	1865	1722	1330	1095	766	1455	1722	982
Simcoe***	1741	1597	1200	957	634	1327	1597	840
Sudbury***	1555	1426	1070	849	550	1184	1426	743
Thunder Bay	1324	1198	857	657	392	964	1198	564
Timiskaming***	1514	1390	1044	830	541	1155	1390	728
Wellington Centre**	1745	1598	1199	957	627	1325	1598	842
Wellington North**	1725	1582	1185	947	624	1312	1582	832