Phytophthora frigida

Abstract

Morphology P. frigida produces sporangia abundantly in 10% nonsterile soil extract when grown under constant light. Most sporangia have prominent papillae. Most isolates have persistent sporangia formed singly or in a loose sympodium. The sporangial shape is predominantly ovoid, although there are other shapes such as globose, ellipsoid, and obpyriform found in some isolates, including some distorted shapes (Fig. 1). The dimensions of sporangia range from 29 to 71 × 20 to 53 µm (avg. 46 × 33 µm), with length-breadth ratios of 1.3 to 1.5 (avg. 1.4). P. frigida produces terminal or intercalary globose chlamydospores that measure 21 to 55 m in diameter (avg. 32 µm) (Fig. 2). P. frigida is heterothallic. Oogonial diameters range from 22 to 37 µm (avg. 30 µm). Antheridia are amphigynous and oospores are globose, aplerotic, and 18 to 31 µm (avg. 24 µm) in diameter (Fig. 3) (Alves et al., 2016).