Submitted to: Crop Protection Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 20, 2010
Publication Date: February 19, 2011
Citation: Dugan, F.M., Hellier, B.C., Lupien, S.L. 2011. Resistance to Penicillium allii in accessions from a National Plant Germplasm System Allium collection. Crop Protection Journal. 30: 483-488. Interpretive Summary: Substantial resistance to Penicillium decay of garlic and onion bulbs is not previously reported. This research documents such resistance in germplasm accessions of several Allium species, distributed within multiple subgenera of the genus Allium. The agents of such decay, species in Penicillium series Corymbifera, have previously been lumped under the name Penicillium corymbiferum, or its synonym, P. hirsutum, but this approach is an over-simplification given current state of Penicillium taxonomy. The disease agents are more numerous, variable in host range and environmental tolerance. This research expands knowledge regarding P. allii, the species most important on garlic. Discussion places results into context of taxonomy of both Penicillium and Allium.
Technical Abstract: Accessions of Allium sativum (garlic), A. ampeloprasum (elephant garlic) and A. acuminatum, A. aflatunense, A. atroviolaceum, A. canadense, A. longicuspis, A. moly, A. ponticum, A. roseum, A. scorodoprasum, A. senescens, A. stipitatum, and Allium sp. (wild or ornamental species) were screened for resistance using Penicillium allii isolates IR13B and/or Mus18C and A. sativum Rose Du Var (as a positive control). Single accessions of A. aflatunense, A. atroviolaceum, A. stipitatum, and Allium sp. remained asymptomatic. Single accessions of A. roseum and A. senescens, two accessions each of A. acuminatum and A. ampeloprasum, and a single accession of A. moly, displayed lesion expansion rates not exceeding 22%, 26%, 46%, 50%, 61%, 67% and 67%, respectively, of positive controls. Single accessions of A. sativum var. ophioscordon and A. scorodoprasum displayed rates not exceeding 68% and 55%, respectively, of positive controls with deep wounding, but did not consistently differ with shallow wounding. Not differing, differing inconsistently or insubstantially from positive controls were accessions in A. canadense, A. sativum or A. longicuspis. A. acuminatum, A. ponticum and A. scorodoprasum displayed rates significantly less than positive controls, but their small bulbs often rotted completely. Results are discussed in the context of current Allium and Penicillium taxonomy.