Force Required to Detach Conidia of Helminthosporium maydis

The force required to break the conidium-conidiophore attachment in Helminthosporium maydis was measured by centrifugation and by a small jet of air. The force which removed half the spores from their stalks was found by both methods to be about 1 × 10⁻² dynes. The corresponding speed of the air jet was about 10 m/sec. Although spores are removed over a range of applied force, most of this spread is accounted for by the variation in spore size. Therefore, the apparent strength of the attachment of conidia to conidiophores, though relatively large, is surprisingly uniform.