Lentil anthracnose: epidemiology, fungicide decision support system, resistance and pathogen races

Figures & data

Table 1. Fungicide decision support system for control of anthracnose (C. lentis) and ascochyta blight (A. lentis) of lentil in western Canada. The threshold value for fungicide application is 50 total risk points.

	Risk points
A. Plant density
Thin (high weed pressure, low yield expectation)	0
Moderate (some weeds, possibly low yield)	5
Normal (about 12 plants per square foot)	10
Dense (more plants than normal, lush growth)	15
B. Number of days with rain in the last 14 days
0 days	0
1–2 days	5
3–4 days	10
5–6 days	15
7 days or more	20
C. Rain in the 5-day weather forecast
Dry	0
Unpredictable	10
Light showers	15
Rain	20
D. Symptoms of anthracnose and ascochyta blight
No visible symptoms	0
Few lesions on lower ½ of the foliage (up to 10% of the leaflets infected)	5
Lesions on lower ½ of foliage (up to 25% of the leaflets infected)	15
Lesions on lower as well as upper foliage	25
Lesions on lower foliage and premature leaf drop characteristic of anthracnose	25
Flowers and/or peduncles infected, characteristic of ascochyta blight	25
Lesions on the stem base	30
Total risk points	From 0 to 85

Fig. 1 (Colour online) a, Premature leaf drop in lentil indicating the presence of initial inoculum of Colletotrichum lentis in the field. b, Lentil plant with lesions on stems and leaflets. c, Close-up of a leaf lesion with microsclerotia, setae and acervuli of C. lentis.

Fig. 2 (Colour online) Cultivated lentil lines (Lens culinaris) in different seed market classes selected for resistance to Colletotrichum lentis race Ct0 and Ct1, the cause of anthracnose in western Canada.