Written and provided by UC IPM. Link to the original article (click here). In brief: Peach root-knot nematode is newly discovered in California, but its current distribution is unknown. Peach root-knot nematode is capable of infecting most Prunus rootstocks currently used in almond and stone fruit production. Rootstocks resistant to previously detected root-knot nematodes may not be resistant to peach root-knot nematode. The California Department of Food and Agriculture rated this nematode as an A quarantine-actionable pest. Contact your local county agricultural commissioner’s office if you suspect you have peach root-knot nematode (uneven and poor tree growth, stunting, and root galls on resistant rootstocks). The peach root-knot nematode (Meloidogyne floridensis) was recently discovered in California and has the potential to infect many of California’s economically important crops. At the time of this writing, it is not clear how wide-spread this nematode is in California. The California Department of Food and Agriculture (CDFA) rated this nematode as an A quarantine-actionable pest. Since the early 1960s, the rootstock Nemaguard and others such as Marianna 2624 and Myrobalan 29C, have protected Prunus crops (almond and stone fruits) from attack by southern root-knot nematodes (M. arenaria, M. incognita, and M. javanica), which are common in California. In contrast, peach root-knot nematode is capable of infecting Nemaguard and peach-almond hybrids. Research in Florida has identified some differences in response among Prunus rootstocks, but peach root-knot nematode itself has variability that allows some populations of it to infect peach and peach-almond hybrids rootstocks that are currently used in California. A consortium of University of California (UC) Cooperative Extension, UC Riverside and CDFA is working with the county agricultural commissioners of the affected counties, the growers, respective crop consultants, and the Almond Board of California to mitigate the potential impacts of peach root-knot nematode. Emphasis will be