With the objective of determining pulse rotation(s) with best economic returns, a trial was conducted in Minto, Manitoba. The pulse rotation trial involved four crops, wheat, canola, pea and lentil in 4 year rotation trials. Yield and disease performance of the different crops were regularly recorded. The following zero-till crop rotations were studied over four yeas, with every crop ("year") being represented each year:

1. Wheat-Wheat-Wheat-Pea
2. Wheat-Canola-Wheat-Pea
3. Wheat-Lentil-Wheat-Pea
4. Wheat-Wheat-Wheat-Lentil
5. Wheat-Wheat-Pea
6. Wheat-Wheat-Lentil
7. Wheat-Canola-Pea
8. Wheat-Lentil-Pea
9. Wheat-Pea
10. Wheat-Lentil
11. *Wheat-Pea-Canola

*Rotation 11 was added in 1995.

The treatments for the pea crop were as follows:

Seed treatment : no

Seed treatment: yes (with Thiram 75 WP, @ 1.4 g product/kg seed)

Foliar fungicide application : no

Foliar fungicide application: yes (with Bravo, @ 4 L/ha in 200 L water)

Following were the rotations involving pea crop:

Analysis of the main effects of seed treatment and foliar fungicide application in 1997 shows that yield of pea crop was unaffected by either seed treatment or foliar fungicide application. The seed treatment also did not influence the levels of foliar disease ratings or the %' of seed infection. The foliar fungicide application, however, significantly reduced the levels of foliar disease ratings as well as % seed infection.

The pea yields were high following wheat, with the exception of W-W-P. Yields were low when pea followed lentil or canola. The rotations differed in levels of foliar disease ratings, but no pea followed lentil or canola. The rotations differed in levels of foliar disease ratings, but no trend could be discerned. There was no significant influence of rotation on the % seed infection.

It appears that when the disease pressure is low, only the rotations but not seed treatments or foliar fungicide applications, make any significant difference in the yield of pea. It may be possible that the wheat stubble conserved more moisture than other preceding crops like canola or lentil, and resulted in better germination and general crop vigor. The foliar disease pressure in 1997 was low (as compared to 1996), thus the seed treatment or the foliar fungicide application did not result in any significant difference in the pea yields

1 foliar disease rating scale 0-9 : 0 = no disease, 9 = severe disease (> 50% leaf surface area covered with lesions on the lower, middle and upper level leaves.

2 Seed grade 1-4 : 1=best seed grade and 4=worst seed grade.

3 values followed by same letters are not significantly different from one another.

4 crops in rotation are w=wheat, c=canola, l=lentil, P=pea.

The treatments for the pea crop were as follows:

Following were the rotations involving lentil crop:

The seed treatment did not influence the yield, % diseased seed or seed grade of lentil, but had resulted in lower foliar disease levels (table 2). Foliar fungicide application on the other hand significantly increased the yield, significantly reduced foliar disease levels and diseased seed, resulting in improved seed grade over the treatments without foliar fungicide application.

Rotations including pea (one year break before lentil) had higher yield than wheat alone and lentil (one year break) in rotation. Apparently only peas had a significantly positive effect on increasing yields or preventing yield reduction associated with wheat or lentil (even if with one year break). Is it possible that nodulation in pea is better than in the lentils? Or is it that some other factor is affected by pea crop which is advantageous to the lentil crop? Some of these speculations could not be answered within the scope of this study.

1 foliar disease rating scale 0-9 : 0 = no disease, 9 = severe disease (> 50% leaf surface area covered with lesions on the lower, middle and upper level leaves.

2 Seed grade 1-4 : 1=best seed grade and 4=worst seed grade.

3 values followed by same letters are not significantly different from one another.

4 crops in rotation are w=wheat, c=canola, l=lentil, P=pea.

There was a significant interaction between seed treatment and foliar fungicide application in influencing the lentil yields but there were no interation as far as foliar disease levels and % seed discoloration due to diseases (Fig. 2a,b &c). Individually, both seed treatment as well as foliar fungicide application increased yields as compared to the control (no seed treatment and foliar fungicide). Seed treatment did not influence the high yields of plots with foliar fungicide application, suggesting that the foliar fungicide application had significantly greater influence which could not be further improved with seed treatment.

There was a significant positive correlation between foliar disease rating and % seed diseased (r=0.36, Prob>F(a=0.05) = 0.0013), and a significant negative correlation between the foliar disease ratings and yield (r---0.38, Prob>F(a=0.05) = 0.00 16). The correlation results also suggest that control of foliar diseases should result in yield increase and reduction in % seed infection.

The treatments for the pea crop were as follows:

Seed treatment: no

Seed treatment: yes (with Vitavax RS, @ 22.4 ml product/kg seed)

Foliar fungicide application: no

Foliar fungicide application: yes (with Benlate, @, 0.61kg/ha in 100 L water)

Following are the rotations involving canola crop:

Analysis of the main effects showed that yield of canola was significantly higher as a result of seed treatment (Vitavax RS) and also foliar fungicide (Benlate) application (Table 3). As expected, seed treatment did not significantly affect the levels of blackleg or sclerotinia diseases; while foliar application of Benlate reduced the incidence and severity of sclerotinia disease. Surprisingly, foliar application of Benlate reduced the blackleg incidence, even though Benlate is not known to directly affect blackleg disease.

None of the rotations had any influence on the levels of blackleg and also sclerotinia diseases. Yield of canola was higher following wheat and than after pea.

There was no significant interaction between seed treatment and foliar Benlate application in influencing yield or diseases. Plots with seed treatment alone or foliar fungicide application alone yielded similarly but higher than untreated plots (Fig. 3). There appeared to be an additive effect of both treatments on yield..

1 blackleg disease rating scale 0-9 : 0 = no disease, 9 = 75 - 100% plants girdled by lesions at the base and killed prematurely, seeds shrivelled, (> 50% plants dead).

2 Sclerotinia disease incidence = % of plants infected, severity = 1-5, where 1= no disease and 5 = 100% of the stem circumference girdled and seed shrivelled.

3 values followed by same letters are not significantly different from one another.

4 crops in rotation are w=wheat, c=canola, l=lentil, P=pea.

The treatments for the wheat crop were as follows:

Seed treatment no

Seed treatment yes (with Vitaflo 280 @ 2.2 ml product/kg seed)

Foliar fungicide application: no

Foliar fungicide application: yes (with Tilt 250 E @ 0.50 kg/ha in 100 1 water)

In the trial there were 11 rotations involving wheat, canola, pea and lentils. The rotations named 1 to 11 are further subdivided into 19 treatments, to study the wheat crop in various stages of the rotation. Thus rotation #1 is subdivided in 1a, 1 b and 1 c treatments, to study wheat crop in the first, second and third year of the rotation with pea in the fourth year. For ease in understanding, the wheat (year) being studied is highlighted by "Upper case and bold letter".

Analysis of main effect of seed treatment of wheat in the pulse rotation trial. suggested that seed treatment resulted in higher yield and lower foliar disease rating, though not significantly different from untreated seed. Seed treatment.significantly reduced the Fusarium Head Blight Index (FHB Index = [incidence * severity]/ 100 ). The seed treatments may have enhanced the crop establishment and vigor and influenced timing of anthesis, and thus avoided the Fusarium head blight inoculum at the critical stage.

The foliar fungicide (Tilt) application had significantly increased the yield and reduced the foliar diseases as well as fusarium head blight. There was a significant negative correlation r = - 0.28, Prob>F=0.000 1) between yield and the foliar diseases.

There was no significant interaction between seed treatment and foliar fungicide application, in influencing yield, foliar diseases and Fusarium head blight. As it can be seen from the three figures (Figs. 4 ab,c) above that foliar fungicide application with seed treatment resulted in the highest yield and lowest diseases while no seed treatment and no fungicide spray resulted in the lowest yield and highest diseases. The effects of seed treatment and foliar fungicide application appear to be additive.

Yields of wheat following pea or following canola in the Wheat-Canola-Wheat-Pea rotation (#2) appeared to be the best rotation for wheat yields (Table 4). Wheat after pulses generally resulted in high yields as compared to wheat after wheat, even thought the rotations involved pulses. The lowest yields were in wheat after wheat in the rotations # 5b (wheat-wheat-pea) and # I c (wheat-wheat-wheat-pea). The rotations did not appear to influence the occurrence of the foliar disease ratings or the Fusarium head blight index, the diseases were reduced by foliar fungicide application and also seed treatment. [ in other words: The levels of foliar diseases and Fusarium head blight did not appear to be influenced by rotation treatments but only by seed treatment and foliar fungicide applications.]