to Rhizoctonia spp. was planted at the University of 

 Massachusetts research farm in S. Deerfield, MA. 

 Ten strawberry cultivars commonly grown in north- 

 eastern North America were planted on July 3. Plots 

 had 20 plants and were replicated 5 times. Individ- 

 ual plots were split, with half of each plot inoculated 

 with multi-nucleate Khizoctonia spp. AG-KB-43). 

 Inoculation was performed by adding to each plant- 

 ing hole 25 ml of oat seed that had been cultured with 

 the Rhizoctonia isolate. Plants were harvested with 

 full root systems the first week of October. Charac- 

 teristics evaluated included plant survival, vegeta- 

 tive growth, root length, and injury to roots. 



In the Rhizoctonia-inoculated plots, 'Jewel,' 

 'Earliglo,' 'Surecrop,' and 'Allstar' survived signifi- 

 cantly better than 'Lester,' 'Midway,' and 'Red Chief 

 (Table 1). Plant growth, as measured by dry weight, 

 was significantly different between cultivars in both 

 inoculated and control plots; however, in order to 

 estimate the effect of the Rhizoctonia, the percent 

 differences between inoculated and non-inoculated 

 plants must be considered. The only cultivars that 

 showed significantly poorer growth under the inocu- 

 lated regime were 'Honeyoye,' 'Kent,' and 'Lester.' 



An index of injury was computed to combine both 

 the effects of Rhizoctonia on plant survival and 

 growth. The difference in survival (inoculated vs. 

 non-inoculated) was multiplied by the percent dif- 

 ference in dry weight (inoculated vs. non-inocu- 



lated). The smaller the index, the better the plant 

 performed under Rhizoctonia inoculation. Using 

 this index, 'Allstar' performed well, and 'Lester" did 

 poorly. 



This trial was done under artificial conditions, 

 but it indicated that 'Lester* is more susceptible to 

 this strain of Rhizoctonia than a cultivar like 'All- 

 star.' However, there is much to learn about the re- 

 lationships of these resultsto black root rot toler- 

 ance. 



Future work will concentrate on a multi-year 

 study with low concentration inoculations of 

 Rhizoctonia spp., including evaluations of plant 

 vigor and fruit production. 



References 



Husain, S.S. and W. E. McKeen. 1963. Rhizoctonia 

 fragariae sp. nov. in relation to strawberry degen- 

 eration in southwestern Ontario. Phytopathology 

 53:532-540. 



Martin, S.B. 1988. Identification, isolation fre- 

 quency, and pathogenicity of anastomosis groups of 

 binucleate Rhizoctonia spp. from strawberry roots. 

 Phytopathology 78:379-384. 



Townshend, J.L. 1962. The root lesion nematode, 

 Pratylenchus penetrans (Cobb 1917) Filip & Stek, 

 1941 in strawberry in the Niagara Peninsula and 

 Norfolk County in Can. J. Plant Sci. 42:728-736. 



From Fleuher, 8. w 1917 

 StnMtb4rry-Gfowutg. MafMillan, 

 KnVaL 



Fruit Notes, Winter, 1991 



21 



