Red rot (<italic>Colletotrichum falcatum</italic> Went.) is one of the most serious diseases in sugarcane and causes considerable losses both in sugarcane yield and juice quality. Several epiphytotics of red rot had occurred in north India sugarcane belt resulting in failure of certain most popular varieties. No systematic work has been done on variation of red rot and its effects on quantitative and qualitative parameters of cane. Keeping all these facts in mind, the present study was undertaken to assess the pathogenic variation in red rot pathogen on differential reaction on differential varieties.Twenty-five standing canes of each differential variety were inoculated with each isolate of pathogen in the month of August by standard plug method of inoculation. A puncture was made in the middle of 3rd or 4th internode from bottom with the help of inoculator which were later sealed withplastic clay after inserting a bit of 7 days old inocula of each isolate of the pathogen. Inoculated canes were split opened longitudinally in the month of January. Nodal transgression, lesion width, occurrence and nature of white spots and condition of tops were noted in case of each isolate. Disease index of each differential variety was calculated on the international scale of (0–9). Nodal transgression (1 = one node crossed, 2 = two nodes crossed and 3 = more than two nodes crossed), lesion with (1 = one third cane width affected, 2 = two third cane width affected and 3 = whole cane width affected), occurrence and nature of white spots (1 = white spot restricted and 2 = white spot progressive) and condition of tops (0 = green and 1 = yellow/dry) were noted in case of each isolates. Disease index was calculated on the 0–9 scale. 0.0–3.0 – R (Resistant), 3.1–6.0 – X (Intermediate), 6.1–9.0 – S (Susceptible).The results showed (<xref ref-type="table" rid="tab001">Table 1</xref>) that the differences among isolates were due to their virulence, while the differences in varieties exhibited their degree of resistance. The differentials BO-91 and SES-594 were resistant against all the test isolates, whereas, varieties CO-997, CO-1148, COJ-64 and Khakai showed susceptible reaction to all the test isolates. Differentials CO-7717, CO-419, CO-62399, COS-767 and Baragua showed differential reaction against all the test isolates. Isolates RR1, RR4 and RR9 showed susceptible reaction on CO-7177, CO-6239 and Baragua while resistant reaction on CO-419 and COS-767. This indicated that isolates RR1, RR4 and RR9 were identical in their pathogenic behaviour. Hence, these isolates were designated as pathotype-1, Isolates RR2, RR6, RR7 and RR10 produced resistant reaction on CO-7717, CO-62399 and Baragua and intermediate reaction on CO-419 and COS-767. These isolates, thus, showed similarity in relation to their pathogenic behaviour. These four isolates, therefore, were grouped into pathotype-2. Similarly, isolates RR3, RR5 and RR8 produced intermediate reaction on CO-7717, susceptible reaction on CO-419, CO-767 and Baragua and resistant reaction on CO-62399 indicating the similarity among these isolates in relation to their virulence. These isolates were therefore, categorized in pathotype-3. Pathogenic variability among the isolates of <italic>C. falcatum</italic> were observed by Kalaimani (<xref ref-type="bibr" rid="bib001">2000</xref>) and Kumar and Virk (<xref ref-type="bibr" rid="bib002">2001</xref>). According to Sidhu <italic>et al</italic>. (<xref ref-type="bibr" rid="bib003">2002</xref>) sugarcane variety COJ-8436 were resistant to 6 isolates of red rot pathogen in Punjab. It is concluded that atleast 3 pathotypes of red rot pathogen are prevalent in Bihar. <table-wrap id="tab001"><label>Table 1</label><caption>Pathological behaviour of red rot isolates on differential varieties</caption><table><thead><tr><th rowspan="3">Cultivars</th><th colspan="10" align="center">Isolates of Colletotrichum flacatum</th></tr><tr><th colspan="10" align="center"><hr /></th></tr><tr><th align="center">RR1</th><th align="center">RR2</th><th align="center">RR3</th><th align="center">RR4</th><th align="center">RR5</th><th align="center">RR6</th><th align="center">RR7</th><th align="center">RR8</th><th align="center">RR9</th><th align="center">RR10</th></tr></thead><tbody><tr><td colspan="11"><hr /></td></tr><tr><td>BO-91</td><td align="center">R(3.0)</td><td align="center">R(2.9)</td><td align="center">R(1.6)</td><td align="center">R(3.0)</td><td align="center">R(1.4)</td><td align="center">R(2.6)</td><td align="center">R(2.8)</td><td align="center">R(1.6)</td><td align="center">R(3.0)</td><td align="center">R(2.6)</td></tr><tr><td>CO-997</td><td align="center">S(8.8)</td><td align="center">S(7.3)</td><td align="center">S(6.5)</td><td align="center">S(8.1)</td><td align="center">S(6.8)</td><td align="center">S(7.2)</td><td align="center">S(7.6)</td><td align="center">S(6.0)</td><td align="center">S(8.2)</td><td align="center">S(7.6)</td></tr><tr><td>CO-7717</td><td align="center">S(8.3)</td><td align="center">R(2.6)</td><td align="center">X(3.8)</td><td align="center">S(8.0)</td><td align="center">X(4.0)</td><td align="center">R(2.4)</td><td align="center">R(2.1)</td><td align="center">X(4.6)</td><td align="center">S(8.0)</td><td align="center">R(2.5)</td></tr><tr><td>CO-419</td><td align="center">R(2.9)</td><td align="center">X(4.5)</td><td align="center">S(7.1)</td><td align="center">R(2.8)</td><td align="center">S(6.9)</td><td align="center">X(4.7)</td><td align="center">X(4.3)</td><td align="center">S(7.2)</td><td align="center">R(3.0)</td><td align="center">X(4.7)</td></tr><tr><td>CO-1148</td><td align="center">S(8.2)</td><td align="center">S(7.3)</td><td align="center">S(6.2)</td><td align="center">S(8.4)</td><td align="center">S(6.3)</td><td align="center">S(7.0)</td><td align="center">S(7.3)</td><td align="center">S(6.6)</td><td align="center">S(7.8)</td><td align="center">S(6.8)</td></tr><tr><td>CO-62399</td><td align="center">S(8.3)</td><td align="center">R(2.6)</td><td align="center">R(1.6)</td><td align="center">S(8.1)</td><td align="center">R(1.9)</td><td align="center">R(2.9)</td><td align="center">R(2.8)</td><td align="center">R(2.4)</td><td align="center">S(8.6)</td><td align="center">R(2.4)</td></tr><tr><td>COS-767</td><td align="center">R(2.8)</td><td align="center">X(4.1)</td><td align="center">S(6.5)</td><td align="center">R(2.8)</td><td align="center">S(6.1)</td><td align="center">X(4.5)</td><td align="center">X(4.8)</td><td align="center">S(6.8)</td><td align="center">R(2.7)</td><td align="center">X(4.4)</td></tr><tr><td>COJ-64</td><td align="center">S(8.4)</td><td align="center">S(7.1)</td><td align="center">S(6.6)</td><td align="center">S(8.2)</td><td align="center">S(6.2)</td><td align="center">S(7.0)</td><td align="center">S(7.0)</td><td align="center">S(6.0)</td><td align="center">S(8.7)</td><td align="center">S(6.5)</td></tr><tr><td>SES-594</td><td align="center">R(3.0)</td><td align="center">R(2.5)</td><td align="center">R(1.9)</td><td align="center">R(3.0)</td><td align="center">R(1.6)</td><td align="center">R(2.3)</td><td align="center">R(2.4)</td><td align="center">R(1.4)</td><td align="center">R(2.9)</td><td align="center">R(2.1)</td></tr><tr><td>Baragua</td><td align="center">S(8.3)</td><td align="center">R(2.5)</td><td align="center">S(6.5)</td><td align="center">S(8.6)</td><td align="center">S(6.1)</td><td align="center">R(2.6)</td><td align="center">R(2.6)</td><td align="center">S(6.3)</td><td align="center">S(8.2)</td><td align="center">R(2.8)</td></tr><tr><td>Khakai</td><td align="center">S(8.0)</td><td align="center">S(7.0)</td><td align="center">S(6.2)</td><td align="center">S(8.4)</td><td align="center">S(6.0)</td><td align="center">S(7.4)</td><td align="center">S(6.8)</td><td align="center">S(6.0)</td><td align="center">S(8.8)</td><td align="center">S(6.5)</td></tr></tbody><tfoot><tr><td colspan="11"><hr /></td></tr><tr><td colspan="11" align="left">Average of 25 canes; Figures in parenthesis are disease index ratings</td></tr><tr><td colspan="11" align="left">R = Resistant, X = Intermediate, S = Susceptible.</td></tr></tfoot></table></table-wrap></sec></body><back><ref-list><title>References

APPS

Annals of Plant Protection Sciences

0971-3573

Society of Plant Protection Sciences

apps-13-2-065

SHORT COMMUNICATION

Pathogenic variability in Colletotrichum falcatum

Minnatullah

Md.

Kumar

Department of Plant Pathology, Rajendra Agricultural University, Bihar, Pusa – 848 125 (Samastipur), India

92005

132500501

Red rot (<italic>Colletotrichum falcatum</italic> Went.) is one of the most serious diseases in sugarcane and causes considerable losses both in sugarcane yield and juice quality. Several epiphytotics of red rot had occurred in north India sugarcane belt resulting in failure of certain most popular varieties. No systematic work has been done on variation of red rot and its effects on quantitative and qualitative parameters of cane. Keeping all these facts in mind, the present study was undertaken to assess the pathogenic variation in red rot pathogen on differential reaction on differential varieties.Twenty-five standing canes of each differential variety were inoculated with each isolate of pathogen in the month of August by standard plug method of inoculation. A puncture was made in the middle of 3rd or 4th internode from bottom with the help of inoculator which were later sealed withplastic clay after inserting a bit of 7 days old inocula of each isolate of the pathogen. Inoculated canes were split opened longitudinally in the month of January. Nodal transgression, lesion width, occurrence and nature of white spots and condition of tops were noted in case of each isolate. Disease index of each differential variety was calculated on the international scale of (0–9). Nodal transgression (1 = one node crossed, 2 = two nodes crossed and 3 = more than two nodes crossed), lesion with (1 = one third cane width affected, 2 = two third cane width affected and 3 = whole cane width affected), occurrence and nature of white spots (1 = white spot restricted and 2 = white spot progressive) and condition of tops (0 = green and 1 = yellow/dry) were noted in case of each isolates. Disease index was calculated on the 0–9 scale. 0.0–3.0 – R (Resistant), 3.1–6.0 – X (Intermediate), 6.1–9.0 – S (Susceptible).The results showed (<xref ref-type="table" rid="tab001">Table 1</xref>) that the differences among isolates were due to their virulence, while the differences in varieties exhibited their degree of resistance. The differentials BO-91 and SES-594 were resistant against all the test isolates, whereas, varieties CO-997, CO-1148, COJ-64 and Khakai showed susceptible reaction to all the test isolates. Differentials CO-7717, CO-419, CO-62399, COS-767 and Baragua showed differential reaction against all the test isolates. Isolates RR1, RR4 and RR9 showed susceptible reaction on CO-7177, CO-6239 and Baragua while resistant reaction on CO-419 and COS-767. This indicated that isolates RR1, RR4 and RR9 were identical in their pathogenic behaviour. Hence, these isolates were designated as pathotype-1, Isolates RR2, RR6, RR7 and RR10 produced resistant reaction on CO-7717, CO-62399 and Baragua and intermediate reaction on CO-419 and COS-767. These isolates, thus, showed similarity in relation to their pathogenic behaviour. These four isolates, therefore, were grouped into pathotype-2. Similarly, isolates RR3, RR5 and RR8 produced intermediate reaction on CO-7717, susceptible reaction on CO-419, CO-767 and Baragua and resistant reaction on CO-62399 indicating the similarity among these isolates in relation to their virulence. These isolates were therefore, categorized in pathotype-3. Pathogenic variability among the isolates of <italic>C. falcatum</italic> were observed by Kalaimani (<xref ref-type="bibr" rid="bib001">2000</xref>) and Kumar and Virk (<xref ref-type="bibr" rid="bib002">2001</xref>). According to Sidhu <italic>et al</italic>. (<xref ref-type="bibr" rid="bib003">2002</xref>) sugarcane variety COJ-8436 were resistant to 6 isolates of red rot pathogen in Punjab. It is concluded that atleast 3 pathotypes of red rot pathogen are prevalent in Bihar. <table-wrap id="tab001"><label>Table 1</label><caption>Pathological behaviour of red rot isolates on differential varieties</caption><table><thead><tr><th rowspan="3">Cultivars</th><th colspan="10" align="center">Isolates of Colletotrichum flacatum</th></tr><tr><th colspan="10" align="center"><hr /></th></tr><tr><th align="center">RR1</th><th align="center">RR2</th><th align="center">RR3</th><th align="center">RR4</th><th align="center">RR5</th><th align="center">RR6</th><th align="center">RR7</th><th align="center">RR8</th><th align="center">RR9</th><th align="center">RR10</th></tr></thead><tbody><tr><td colspan="11"><hr /></td></tr><tr><td>BO-91</td><td align="center">R(3.0)</td><td align="center">R(2.9)</td><td align="center">R(1.6)</td><td align="center">R(3.0)</td><td align="center">R(1.4)</td><td align="center">R(2.6)</td><td align="center">R(2.8)</td><td align="center">R(1.6)</td><td align="center">R(3.0)</td><td align="center">R(2.6)</td></tr><tr><td>CO-997</td><td align="center">S(8.8)</td><td align="center">S(7.3)</td><td align="center">S(6.5)</td><td align="center">S(8.1)</td><td align="center">S(6.8)</td><td align="center">S(7.2)</td><td align="center">S(7.6)</td><td align="center">S(6.0)</td><td align="center">S(8.2)</td><td align="center">S(7.6)</td></tr><tr><td>CO-7717</td><td align="center">S(8.3)</td><td align="center">R(2.6)</td><td align="center">X(3.8)</td><td align="center">S(8.0)</td><td align="center">X(4.0)</td><td align="center">R(2.4)</td><td align="center">R(2.1)</td><td align="center">X(4.6)</td><td align="center">S(8.0)</td><td align="center">R(2.5)</td></tr><tr><td>CO-419</td><td align="center">R(2.9)</td><td align="center">X(4.5)</td><td align="center">S(7.1)</td><td align="center">R(2.8)</td><td align="center">S(6.9)</td><td align="center">X(4.7)</td><td align="center">X(4.3)</td><td align="center">S(7.2)</td><td align="center">R(3.0)</td><td align="center">X(4.7)</td></tr><tr><td>CO-1148</td><td align="center">S(8.2)</td><td align="center">S(7.3)</td><td align="center">S(6.2)</td><td align="center">S(8.4)</td><td align="center">S(6.3)</td><td align="center">S(7.0)</td><td align="center">S(7.3)</td><td align="center">S(6.6)</td><td align="center">S(7.8)</td><td align="center">S(6.8)</td></tr><tr><td>CO-62399</td><td align="center">S(8.3)</td><td align="center">R(2.6)</td><td align="center">R(1.6)</td><td align="center">S(8.1)</td><td align="center">R(1.9)</td><td align="center">R(2.9)</td><td align="center">R(2.8)</td><td align="center">R(2.4)</td><td align="center">S(8.6)</td><td align="center">R(2.4)</td></tr><tr><td>COS-767</td><td align="center">R(2.8)</td><td align="center">X(4.1)</td><td align="center">S(6.5)</td><td align="center">R(2.8)</td><td align="center">S(6.1)</td><td align="center">X(4.5)</td><td align="center">X(4.8)</td><td align="center">S(6.8)</td><td align="center">R(2.7)</td><td align="center">X(4.4)</td></tr><tr><td>COJ-64</td><td align="center">S(8.4)</td><td align="center">S(7.1)</td><td align="center">S(6.6)</td><td align="center">S(8.2)</td><td align="center">S(6.2)</td><td align="center">S(7.0)</td><td align="center">S(7.0)</td><td align="center">S(6.0)</td><td align="center">S(8.7)</td><td align="center">S(6.5)</td></tr><tr><td>SES-594</td><td align="center">R(3.0)</td><td align="center">R(2.5)</td><td align="center">R(1.9)</td><td align="center">R(3.0)</td><td align="center">R(1.6)</td><td align="center">R(2.3)</td><td align="center">R(2.4)</td><td align="center">R(1.4)</td><td align="center">R(2.9)</td><td align="center">R(2.1)</td></tr><tr><td>Baragua</td><td align="center">S(8.3)</td><td align="center">R(2.5)</td><td align="center">S(6.5)</td><td align="center">S(8.6)</td><td align="center">S(6.1)</td><td align="center">R(2.6)</td><td align="center">R(2.6)</td><td align="center">S(6.3)</td><td align="center">S(8.2)</td><td align="center">R(2.8)</td></tr><tr><td>Khakai</td><td align="center">S(8.0)</td><td align="center">S(7.0)</td><td align="center">S(6.2)</td><td align="center">S(8.4)</td><td align="center">S(6.0)</td><td align="center">S(7.4)</td><td align="center">S(6.8)</td><td align="center">S(6.0)</td><td align="center">S(8.8)</td><td align="center">S(6.5)</td></tr></tbody><tfoot><tr><td colspan="11"><hr /></td></tr><tr><td colspan="11" align="left">Average of 25 canes; Figures in parenthesis are disease index ratings</td></tr><tr><td colspan="11" align="left">R = Resistant, X = Intermediate, S = Susceptible.</td></tr></tfoot></table></table-wrap></sec></body><back><ref-list><title>ReferencesKalaimani

(2000). Pathogenic variability of red rot caused by C falcatum Went. in Tamil Nadu. Ind. Sugar 49 (10): 841-846.Kumar

Virk

K.S.

(2001). Identification of sources of resistance to four different pathotypes of C falcatum. Indian Phytopath. 54 (4): 2001.Sidhu

G.S.

Uppal

S.K.

Sharma

B.K.

(2002). Reaction to red rot and cane quality of COJ-8436 cultivar of sugarcane in Punjab. Cooperative Sugar 33 (7): 573-575.Kalaimani

(2000) Pathogenic variability of red rot caused by C. falcatum Went. in Tamil Nadu. Ind. Sugar 49 (10): 841–846.Kumar