A Simple and Efficient Inoculation Method for Fusarium Dry Rot Evaluations in Potatoes
Chen, D., Nahar, K., Bizimungu, B., Soucy, S., Peters, R.D., De Koeyer, D., Dickison, V. (2020). A Simple and Efficient Inoculation Method for Fusarium Dry Rot Evaluations in Potatoes. American Journal of Potato Research, [online] 97(3), 265-271. http://dx.doi.org/10.1007/s12230-020-09774-4
Plain language summary
Plain language summary: Fusarium dry rot (FDR), caused by fungal pathogens (germs), Fusarium species, is an important potato disease world-wide, causing post-harvest rotting and seed-piece decay after planting. The estimated annual loss to FDR ranged from 6 to 20%. Breeding potato varieties resistant to the disease is currently not very efficient because the traditional inoculation methods are low efficiency and time consuming. The most commonly used method is the cork borer wounding method. But it consists of multiple steps and is time consuming and easy to get cross-contamination. We developed a new inoculation method, the plastic crew wounding method, to replace the traditional cork borer inoculation method. In six trials with eight potato genotypes conducted in the winters of 2018 and 2019, tuber dry rot, in the same sets of the tubers, produced by using the plastic screw was comparable to that produced by using the cork borer method. The plastic screw inoculation method has advantages over the other reported inoculation methods including the cork borer wounding method. It condenses the wounding, introduction of germs and wound sealing into a single step, as compared to multiple steps needed in other reported inoculation methods. As a result, it significantly shortens the inoculation time and eliminate the germ cross-contamination among tubers by the wounding tools. The new method can be efficiently used to study the capacity of the germs causing potato tuber rot, to screen resistance of the potato breeding lines against the germs for variety development.
Fusarium dry rot (FDR), caused by Fusarium species is an important potato disease world-wide and causes post-harvest rotting and seed-piece decay after planting. In this study, we compared two inoculation methods - cork borer wounding (CBW) and plastic screw wounding (PSW) – for consistent and reproducible disease development in potatoes. A plastic screw was used as a tool to make nearly identical wounds and simultaneously deliver similar quantities of inoculum into tubers, while at the same time sealing the wound in a single step. The PSW method resulted in tuber dry rot severities comparable to that obtained using the traditional CBW method. Tuber rot severities obtained using the two methods were highly correlated in the same sets of tubers, among the three inoculations conducted at different time periods (r values ranging from 0.56–0.95; p < 0.001) for both years of the study. The PSW inoculation method condensed the wounding, inoculum delivery and wound sealing into a single step, thus saving considerable time when compared to the CBW inoculation method. The single use of individual plastic screws can also prevent cross-contamination from non-target microorganisms, which may reside inside the surface-sterilized tubers. The PSW method can be efficiently used to screen potato breeding lines for resistance to Fusarium dry rot.