This new species is characterized by unbranched sporangiophores, and non-papillate, sub-globose to ovoid sporangia that are occasionally free from the sporangiophore with medium length pedicels. Despite using a number of oospore inducing techniques, oogonia/antheridia [sexual structures] were not observed in isolates of P. pinifolia (Duran et al. 2008).

Aerial parts of Pinus radiata including needles, needle bases and stems of young trees. The habitat of Phytophthora pinifolia is unusual in that it is the only species of this genus known to infect green shoots and needles of a Pinus sp. (Duran et al. 2008). Trees of all ages are susceptible to disease, from seedlings to mature trees.

There are many questions regarding the biology of the pathogen that remain to be answered. While it is assumed that the sporangia are the infective propagules, this has yet to be shown experimentally. These structures were not abundant in culture and more natural conditions under which to produce them will need to be developed. Likewise, infection studies with zoospores and the infection biology and life cycle of the pathogen remain to be understood (Duran et al. 2008).

Phytophthora pinifolia causes devastating needle blight disease on Monterey pine (Pinus radiata). According to Wingfield (2007) “The disease, locally referred to as Daño Foliar del Pino (DFP), is typified by the relatively rapid death of needles and subsequent defoliation of trees. Infections usually begin to appear in late autumn and co-incident with the onset of rain. Infected needles typically display distinct resinous bands on their laminas. Where infections reach the needle bases, copious amounts of resin exude from the points of attachment with the stems and dead needles fall from the trees. New needle growth in the following season is typically not affected and trees appear to recover unless a new season of infection occurs the following year. Newly planted seedlings and naturally regenerated plants die in the first year of growth.” After a number of years of successive infection mature trees may die, probably caused by increased susceptibility to opportunistic infection by fungi such as Diplodia pinea. In Chile P. pinifolia is the most important problem affecting P. radiata plantations, and poses a serious threat to the local forestry industry (EPPO 2009).

Preventative: It seems that only Pinus radiata is affected by Phytophthora pinifolia. Thus other Pinus species may be chosen for plantation development. There is also evidence that different genotypes of P. radiata differ in susceptibility, meaning that less susceptible varieties could be chosen for plantation (Duran et al. 2008).

Chemical: There are possibilities for use of fungicides to control the disease (Duran et al. 2008).