Crop Report – September 14, 2022

Tar Spot and Fungicide Application Timings!

Although tar spot was detected in Ontario in the first week of July the past two years, 2022 is much different than 2021 and shows the importance of environmental conditions for disease development. Remember, this holds true for any disease! The big difference was the dry conditions early and shortened leaf wetness periods which delayed tar spot establishment until later (post-tassel). Areas along the north shore of Lake Erie (Essex through Haldimand-Norfolk) are seeing tar spot at higher levels compared to other areas. 

OMAFRA and UG Ridgetown Campus results in 2021 supported U.S. data that fungicides applied between tasseling (VT) and silking (R1) provided optimum control of tar spot. Fortunately, the optimum application timing for effective tar spot fungicides is the same for other common leaf diseases like northern corn leaf blight and especially Gibberella ear rot (DON). 

This year there have been a lot of questions around fungicide application timing for fields at risk of late season tar spot infection. In OMAFRA tar spot trials in Rodney, ON with Dr. Dave Hooker (UGRC) there are definite differences in tar spot control as expected since fungicide efficacy is largely dependent on fungicide selection and application timing. The images below illustrate some of the differences to date. The pre-tassel applications (7 to 12 leaf) did not reduce visual symptoms of tar spot compared to non-sprayed check (Figure 1) and plants are prematurely shut down which is expected since product wouldn’t be available when needed (Figure 22). The VT/R1 application again provided good control for those fungicides which have demonstrated good tar spot control, but some late tar spot is present (Figure 3). Similarly, later applications at R3 (milk) and R4 (dough) either alone or as a second application have shown good control (Figure 4).  

Will these observations between VT/R1 and later applications result in significant yield differences and will the “Return on Investment (ROI)” cover a late or second fungicide application? We cannot wait till these and other tar spot trials are harvested so we can answer these questions and more! Stayed tuned for updated fungicide performance information!!

Fall is BEST Time to Sample for SCN!

Soybean harvest has begun and for many growers, managing soybean cyst nematode means planting SCN resistance varieties BUT effective SCN management does not end when you have selected your soybean varieties! It is imperative to not only know your SCN population levels in each of your fields but what is happening to those levels over time and it begins with SCN soil testing!

The fall is a perfect time to sample harvested soybean fields or those which will be planted to soybeans in 2022. A fall sample takes into account any significant SCN population changes that have occurred during the growing season. If it’s the first-time sampling a field, the results provide you a baseline for future comparison. If you already have a baseline, the SCN test provides critical information.

If your SCN levels are decreasing, this could indicate your management program is working. If your is SCN levels are rising, this is a big red flag that the problem is getting worse and could get out of hand, costing you significantly in lost yield, dollars and sleep! If you do not know what is happening to your SCN population levels in your fields over time, your efforts may be wasted. One of the most important decisions a producer can make concerning this devastating pest is to take a SCN soil test.

For more information, visit the SCN Coalition website at www.thescncoalition.com or OMAFRA Agronomy Guide Publication 811 at www.omafra.gov.on.ca/english/crops/pub811/p811toc.html).

Ontario Nematode Survey Request for Samples!

OMAFRA specialists Albert Tenuta (Field Crop Pathologist) and Katie Goldenhar (Horticultural Crop Pathologist) are coordinating a nematode survey, targeting field crop and horticultural crop fields across the province. Nematodes present a significant and ongoing threat to plant health in Ontario and can result in significant economic and production losses. The primary objective of this 2-year CAP funded project is to update provincial nematode distribution maps as well as establish baseline data, for six different nematode species including soybean cyst nematode, root lesion or other nematode species. These results will support the enhancement of current nematode Best Management Practices for field and horticultural crop farmers, helping to improve the economic and sustainability of crop production in Ontario. Participating in the nematode survey is FREE, easy and soil samples can be collected specifically for nematode testing such as SCN or alternatively, soil samples collected for soil fertility can be split, with subsamples submitted for nematode testing. If you would like more information on the Nematode Survey, please contact Albert Tenuta (albert.tenuta@ontario.ca) or Katie Goldenhar (katie.goldenhar@ontario.ca).

Ontario Diagnostic Day Videos Now Available!

It was great getting back together in-person on July 20^th and 21^st, 2022 at the UG Ridgetown Campus for the Ontario Crop Diagnostic Days which combined the Southwest (Ridgetown), Elora and Eastern Ontario (Winchester) Crop Diagnostic Days into one hybrid provincial event! Thanks to all those who attended and our sponsors! As promised the 8 in-field session recordings have begun to be rolled out at realagriculture.com/ontariodiagnosticdays. Those CCA’s unable to attend in person will be able to register for the virtual event to receive their CEU credits (bdc.ridgetownc.com).

Weather Data – September 4 – 10, 2022

Location	Year	Highest Temp (°C)	Lowest Temp (°C)	Rain (mm)	Rain (mm) April 1st	GDD 0C April 1st	GDD 5C April 1st	CHU May 1st
Harrow	2022	26.5	9.2	2.5	387	2893	2111	3268
	2021	29.6	9.8	4.3	456	2915	2118	3183
	10 YR Avg. (2011-20)	26.3	13.3	20.7	496	2869	2056	3252
Ridgetown	2022	28.7	8.3	2.5	277	2748	1973	3033
	2021	28.2	7.1	4.0	440	2754	1966	2997
	10 YR Avg. (2011-20)	25.6	11.6	24.6	452	2704	1896	3030
London	2022	28.3	10.2	4.8	318	2681	1911	2962
	2021	25.6	9.9	31.5	382	2739	1955	2967
	10 YR Avg. (2011-20)	25.1	11.4	28.4	471	2677	1874	3006
Brantford	2022	28.0	10.0	3.1	287	2689	1913	2903
	2021	28.0	7.9	43.4	361	2709	1924	2905
Welland	2022	26.6	11.7	45.9	361	2742	1956	3048
	2021	26.0	9.2	46.6	369	2724	1935	2968
	10 YR Avg. (2011-20)	26.2	12.1	23.3	414	2698	1893	3036
Elora	2022	28.6	9.1	0.0	254	2471	1708	2670
	2021	25.0	7.2	54.2	340	2509	1734	2700
	10 YR Avg. (2011-20)	23.9	9.3	31.4	467	2422	1631	2691
Mount Forest	2022	27.1	8.8	0.8	374	2460	1703	2706
	2021	24.7	7.1	54.6	454	2511	1739	2717
	10 YR Avg. (2011-20)	23.7	9.5	33.0	481	2409	1626	2708
Peterborough	2022	27.5	8.1	0.0	324	2474	1696	2675
	2021	24.6	6.7	47.9	349	2520	1733	2688
	10 YR Avg. (2011-20)	24.9	7.0	21.7	413	2454	1663	2687
Kemptville	2022	28.9	11.4	4.0	457	2633	1836	2891
	2021	24.7	9.5	25.2	313	2701	1909	2874
	10 YR Avg. (2011-20)	24.8	8.7	22.3	460	2577	1787	2871
Earlton	2022	27.9	2.2	0.0	351	2231	1503	2464
	2021	20.9	5.4	40.8	514	2334	1567	2457
	10 YR Avg. (2011-20)	21.3	6.2	22.8	413	2102	1395	2336
Sudbury	2022	27.4	7.1	0.0	318	2276	1538	2557
	2021	21.7	6.8	19.2	414	2370	1604	2535
	10 YR Avg. (2011-20)	22.6	7.3	18.8	444	2252	1522	2561
Thunder Bay	2022	26.8	0.8	20.5	477	2025	1324	2214
	2021	24.1	5.9	12.2	274	2227	1474	2360
	10 YR Avg. (2011-20)	21.7	4.8	16.8	404	2018	1299	2227
Fort Frances	2022	26.7	2.3	0.9	576	2107	1408	2366
	2021	25.6	2.0	13.4	265	2308	1549	2464
	10 YR Avg. (2011-20)	22.2	5.4	15.2	406	2144	1408	2379