Table 2.
Cultural characteristics and pathogenic profiles of maize leaf blight (MLB)-causing isolates from Zea mays collected from different agro-ecological zones under maize production on PDA at 27 ± 1 °C.
| S N $ | Isolate | Size of Conidia (µm) and Septations * | Radial Growth (in mm) ** | Disease Score *** | Incubation Period (in h) ∞ | Colony Texture # | Colour of Colony ** | Disease Index β (PDI) | ||
|---|---|---|---|---|---|---|---|---|---|---|
| Length (µm) | Width (µm) | No. of Septa | ||||||||
| 1 | BmPhRj4 | 9.8 (6.54–17.86) | 3.4 (2.25–4.63) | 2.7 (2–5) | 47.5 (++) | 1.5 | 72 (Type-I) | Rr/Nz/Irm | Light black | 30 (MV) |
| 2 | BmBjUa1 | 16.9 (10.68–20.84) | 4.1 (3.72–4.45) | 7.1 (5–8) | 58.5 (++) | 2.6 | 72 (Type-II) | Rr/Nz/Rm | Black | 52 (MoV) |
| 3 | BmBsRj4 | 12.7 (7.79–22.78) | 4.9 (4.36–5.26) | 4.7 (3–6) | 71.4 (+++) | 2.3 | 48 (Type-III) | Sap/Nz/Rm | Black | 46 (MV) |
| 4 | BmDhBh3 | 14.4 (11.91–16.66) | 4.5 (3.91–5.43) | 3.7 (3–5) | 51.1 (++) | 3.7 | 72 (Type-I) | Rap/Nz/Rm | Black | 74 (HV) |
| 5 | BmCgRj4 | 14.8 (9.26–20.96) | 4.3 (2.48–4.78) | 4.2 (2–9) | 72.3 (+++) | 2.9 | 48 (Type-II) | Rr/Nz/Rm | Light black | 58 (MoV) |
| 6 | BmPnDl2 | 19.3 (13.27–21.36) | 5.0 (3.91–5.73) | 4.3 (3–7) | 68.8 (++) | 2.7 | 72 (Type-III) | Rr/Z/Irm | Black | 54 (MoV) |
| 7 | BmDnRj4 | 11.1 (6.52–14.94) | 4.7 (3.63–5.51) | 3.0 (2–5) | 69.0 (++) | 1.9 | 48 (Type-II) | Sap/Nz/Rm | Light grey | 38 (MV) |
| 8 | BmKgUa1 | 10.1 (7.34–15.43) | 4.5 (3.89–5.46) | 3.1 (2–6) | 63.4 (++) | 2.4 | 76 (Type-II) | Sap/Nz/Rm | Dark grey | 48 (MV) |
| 9 | BmKrHr2 | 15.1 (19.25–11.03) | 4.4 (4.19–4.93) | 6.1 (4–7) | 74.3 (+++) | 3.5 | 48 (Type-I) | Sap/Nz/Rm | Dark grey | 70 (HV) |
| 10 | BmKtRj4 | 13.0 (8.92–19.4) | 3.9 (2.54–5.22) | 3.7 (2–5) | 54.3 (++) | 1.7 | 96 (Type-III) | Sap/Nz/Rm | Black | 34 (MV) |
| 11 | BmLdPj2 | 14.3 (8.78–23.57) | 4.4 (2.55–5.77) | 5.1 (3–6) | 37.4 (+) | 4.3 | 72 (Type-II) | Rr/Nz/Irm | Dark grey | 86 (HV) |
| 12 | BmPtUa1 | 14.7 (11.89–17.74) | 4.9 (4.23–5.43) | 4.1 (3–4) | 45.5 (++) | 3.2 | 72 (Type-II) | Rr/Nz/Rm | Dark grey | 64 (MoV) |
| 13 | BmMyKa6 | 13.1 (10.77–17.03) | 3.8 (2.46–4.78) | 4.1 (3–4) | 78.9 (+++) | 2.7 | 72 (Type-IV) | Sap/Z/Rm | Light grey | 54 (MoV) |
| 14 | BmMdKa6 | 11.6 (6.88–15.32) | 3.6 (4.12–5.36) | 3.8 (4–2) | 81.8 (+++) | 1.7 | 72 (Type-I) | Sap/Z/Rm | Light grey | 34 (MV) |
| 15 | BmGdGj5 | 7.6 (6.83–9.77) | 3.1 (3.61–4.52) | 1.0 (1–3) | 79.3 (+++) | 3.3 | 48 (Type-I) | Rr/Nz/Rm | Black | 66 (MoV) |
| 16 | BmAdGj5 | 12.1 (8.23–15.98) | 4.3 (3.84–5.86) | 3.0 (2–9) | 51.6 (++) | 4.5 | 72 (Type-VI) | Rap/Nz/Rm | Black | 90 (HV) |
| 17 | BmLhRj4 | 17.2 (10.33–23.13) | 3.7 (2.44–4.57) | 5.0 (4–8) | 59.3 (++) | 3.7 | 72 (Type-III) | Rr/Z/Irm | Dark grey | 74 (HV) |
| 18 | BmSkRj4 | 16.8 (9.78–20.11) | 3.1 (2.98–4.91) | 3.0 (2–8) | 37.7 (+) | 3.6 | 72 (Type-V) | Sap/Nz/Rm | Dark grey | 72 (HV) |
| 19 | BmSmBh3 | 7.8 (6.12–10.11) | 6.1 (4.21–7.93) | 2.0 (2–6) | 42.6 (++) | 4.3 | 76 (Type-V) | Sap/Z/Rm | Dark grey | 86 (HV) |
| 20 | BmAmRj4 | 18.6 (7.33–21.67) | 5.8 (3.22–8.44) | 6.0 (4–8) | 67.3 (++) | 4.1 | 72 (Type-IV) | Rr/Nz/Irm | Black | 82 (HV) |
| CD at 5% | 6.2 | 1.2 | 2.0 | 1.28 | 1.1 | |||||
* Range is given in parentheses. ** Radial growth was recorded 10 days after inoculation (DAI) and expressed as an average of 3 replications; (+) = Slow growth (30–40 mm), (++) = Medium growth (40–70 mm), (+++) = Fast growth (70–90 mm). # Rr = rough raised, Z = Zonation, Nz = no zonation, Rm = regular margin, Rap = rough appressed, Irm = irregular margin; Sap = smooth appressed, Sr = smooth raised. *** Disease score expressed as an average of 10 replications using a rating scale of 1–5 (Payak and Sharma, 1983). β PDI (Percent Disease Index) expressed as an average of 10 replications using the formula PDI = sum of all ratings/maximum disease rating × 100; PDI > 70–100%—highly virulent (HV), PDI > 50–69%—Moderate virulence (MoV), PDI > 20–49%—Mild virulence (MV). ∞ Symptoms: Type-I, Small, dot–like yellowish necrotic lesions scattered away from midrib; Type-II, Dot–like, tan–colored lesions scattered profusely on the leaf surface; Type-III, Elongated, nearly long strip, tan–colored lesions restricted by veins; Type-IV, Long, narrow tan–colored linear lesions; Type-V: Circular lesions that were larger than the Type I lesions with purplish margins; Type-VI: Very large necrotic lesions along the length of leaf margins or parallel to midrib. $ Based on phylogeny, serial numbers (SN) 1 to 13 were identified as Bipolaris maydis, SN 14 as B. zeicola, SN 15 and 16 as Curvularia papendorfiii, SN 17 as C. sporobolicola, SN 18 as C. siddiquii, SN 19 as Curvularia sp. (C. graminicola–like), and SN 20 as Alternaria sp.