Manag­ing plant dis­ease in the fu­ture by scout­ing now

Prairie Post (East Edition) - - Farm News - BY KAELEY KINDRACHUK, SASK. CROPS EX­TEN­SION SPE­CIAL­IST, OUT­LOOK

Manag­ing plant dis­ease is a com­plex is­sue that takes plan­ning and con­sid­er­a­tion in or­der to stay on top of it year af­ter year.

Check­ing fields is a crit­i­cal piece of the puz­zle and one that must hap­pen on a reg­u­lar ba­sis. Early in the sea­son we start mon­i­tor­ing our seedlings to en­sure that they stay healthy and clean.

The scout­ing will con­tinue through­out the sea­son un­til just be­fore har­vest; how­ever, to mon­i­tor for two dis­eases that have the po­ten­tial for high yield loss, we need to keep scout­ing and be able to dif­fer­en­ti­ate be­tween the two.

Both Black­leg and Clu­b­root can cause eco­nomic losses in canola if left un-mon­i­tored.

To check for these plant dis­eases, look at the field as a whole, look­ing for patches of pre-ma­ture ripen­ing or lodg­ing in low ar­eas and near the field en­trance. This will give an in­di­ca­tion that some­thing is wrong and where to start look­ing.

The eas­i­est way to iden­tify Black­leg is later in the sea­son, around the time of swathing, al­though you can watch cotyle­dons ear­lier for leaf le­sions. You will want to sam­ple 20 plants in five spots through­out a “W” pat­tern in the field for a to­tal of 100 plants.

To check for Black­leg, pull up each plant and clip the bot­tom of each stem at ground level. If the plant is in­fected with Black­leg, you will see black or brown within the cross-sec­tion of the stem.

Rate each stem on a zero to five scale based on the sever­ity of dam­age that you find. The scale with a vis­ual guide can be found at

https://www.saskcanola.com/quad­rant/me­dia/files/re­source/pdfs/BLACK­LEG-SP-Brochure.pdf. Once the plants have been rated, add up each of the num­bers and di­vide that by the num­ber of plants with symp­toms.

If your av­er­age rat­ing is a 1.5 or higher, it’s a good sign that Black­leg re­sis­tance in that va­ri­ety is no longer ef­fec­tive on races found in that field.

Some­times, you may also be able to see vis­ual symp­toms on the plants as le­sions can oc­cur on stems and leaves and will be dot­ted with py­c­ni­dia, which look like pep­per sprin­kled through­out the le­sion. Black­leg can in­fect sus­cep­ti­ble va­ri­eties of canola any­time through­out the plants’ life­cy­cle. Some man­age­ment op­tions for Black­leg in­clude keep­ing a longer crop­ping ro­ta­tion and ro­tat­ing va­ri­eties when you do grow canola.

While pulling plants to clip the stems for Black­leg, don’t for­get about ex­am­in­ing the roots for Clu­b­root galls. If Clu­b­root is present at low lev­els, the galls will start form­ing on the lat­eral roots. If the Clu­b­root dis­ease is at higher lev­els, galls will form on the tap­root, in­hibit­ing the plants abil­ity to up­take nu­tri­ents and water.

In most cases, Clu­b­root is first iden­ti­fied at the field en­trance as the pathogen moves any way that soil doesin­clud­ing on equip­ment. Pull 20-30 plants in a “U” shaped area at the field en­trance and check the roots. The lower ar­eas of the field are of­ten wet­ter and the con­di­tions may be more con­ducive for dis­ease de­vel­op­ment.

An­other way to mon­i­tor for Clu­b­root is by tak­ing a DNA-based soil test and send­ing it to a lab for anal­y­sis. Clu­b­root is eas­ier to man­age when we find the pathogen at low lev­els through a soil test.

You can man­age it by crop ro­ta­tion, Clu­b­root re­sis­tant va­ri­eties and us­ing pre­ven­ta­tive ac­tions. If vis­ual symp­toms of Clu­b­root are found, pro­duc­ers can work with a pro­fes­sional agrol­o­gist to cre­ate a Clu­b­root Man­age­ment Plan.

For more in­for­ma­tion, please visit www.saskatchew­an.ca or www.clu­b­root.ca.

Photo con­trib­uted

Long- term man­age­ment plans needed to guard against dis­eases such as Black­leg and Clu­b­root.

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