Cleistocactus strausii
Silver Torch cactus can thrive in low-nitrogen soil without facing the consequences of low nitrogen. Too much water will make the plant weak and lead to root rot. 
Least Concern. This cactus is locally abundant in its native land and has few local threats to its survival.
This cactus can be propagated by cuttings or seed.
Phytophthora megasperma
Water moulds in the "P. megasperma" complex can be found on a multitude of host plants, including many agricultural crops. It has been noted on soybeans, kiwifruit ("Actinidia deliciosa"), horse chestnut ("Aesculus hippocastanum"), hollyhock ("Alcea rosea"), asparagus ("Asparagus officinalis"), "Brassica oleracea", crops such as cabbage, cauliflower, safflower ("Carthamus tinctorius"), Port Orford cedar ("Chamaecyparis lawsoniana"), chickpea ("Cicer arietinum"), carrot ("Daucus carota"), carnation ("Dianthus caryophyllus"), eucalyptus ("Eucalyptus" spp.), walnut ("Juglans regia"), apple ("Malus domestica"), pines ("Pinus" spp.), stone fruit such as apricot, cherry, plum, and peach, Douglas fir ("Pseudotsuga menziesii"), sugarcane ("Saccharum officinarum"), and potato ("Solanum tuberosum").