Ever wonder why we only have one commercial rootstock that we use for Florida peach production? It’s because of a type of root-knot nematode found only here in Florida. In fact, it’s scientific name is Meloidogyne floridensis.
If you have it in your orchard, you might see short shoot growth, early bloom, and a general delay in fruit development (see below). The tree on the right was found to have nematode galls on the root system that was affecting the tree growth. Successive years of weak growth can cause tree collapse, and will require removal and replanting.
Help Us Out!
So, what can be done? First things first, we need some help! Dr. Janete Brito at FDACS, DPI in Gainesville would like to conduct a survey of growers orchards.
Here is her request:
Scientists of FDACS, Division of Plant Industry, University of Florida, IFAS and other research agencies are joining forces through a cooperative Farm Bill agreement to study and identify plant-parasitic nematodes associated with peach trees in Florida peach orchards. So far, the potential risk posed by these nematodes to the new peach industry in Florida has not been fully assessed because of lack of information on their identity and distribution in the state. Scientists involved in this cooperative project are confident that an intensive nematode survey in Florida peach followed by accurate morphological and molecular analyses of plant-parasitic nematodes found will provide precise information on the species that parasitize peach in Florida. Additionally, an associated survey for detection of plum pox virus (PPV) will be carried out. The results of these surveys will provide information about the incidence of these pathogens in Florida peach.
The sites to be surveyed for nematodes will include existing peach orchards, nurseries and land destined to peach production, including abandoned citrus groves. The support and cooperation of the peach growers in the form of access to orchards, nurseries and other sites to be sampled are much needed for the success of this project. As permission and access to the sites to be surveyed is granted, a timetable and strategy will be developed trying to minimize potential interference with the activity of peach growers involved in the survey. Scientists are hoping that this initiative will receive a favorable reception by the Florida peach industry. Peach growers wishing more information about this cooperative project or willing to provide access to their orchards for the survey should contact Dr. Janete Brito, FDACS nematologist; phone: (352)395-4752; e-mail:janete.brito@freshfromflorida. com.
Thank you in advance for helping to figure out where these nematodes are, so that we can target control methods. If you have any questions, please let Dr. Brito know! Cheers, Mercy
We have a great agenda planned with presentations on postharvest management of peaches, the impact of our current climate on the southeastern U.S., new AgroClimate apps, chill accumulation and options for management in peaches, crop insurance progress and options, and the quest to find out why our rootstock, ‘Flordaguard’ is resistant to nematodes.
Lunch will be freeagain this year, thanks to our very generous sponsors, which include: Philip Rucks Citrus Nursery, ColdPICK Technologies, Maxijet, Inc., Island Grove Ag Products, Growers Fertilizer Corporation, KeyPlex, Valent Biosciences, Syngenta, and Carden and Associates, Inc.
Please register by April 15th, so that we have an accurate headcount for lunch. There is a place on the registration form to input any dietary restrictions so that we can get the appropriate lunch for you and you won’t go hungry!
As I have traveled over the past six months or so, I have seen many trees that possibly have nematode issues; that is the trees flush out with early growth and sometimes bloom early, yet they lag behind later in the year from normal trees (Figure 1).
Figure 1. Nematode-affected tree showing reduced growth, due to an outcross of ‘Flordaguard’ rootstock.
What do you do if you suspect that nematodes have infected a tree in your orchard?
The first thing that I usually do is politely ask the grower if it’s ok to pull up their tree. Often you will notice the either early or delayed growth from the rest of the orchard approximately one year from planting, so the trees are easily pulled up from the soil. In many cases, we end up finding nematode galls throughout the root system (Figure 2). These root knot galls are caused by the peach root knot nematode (Meloidogyne floridensis). If you do find these, then dispose of the tree and replant with a new tree that is budded onto “true-to-type” ‘Flordaguard’ rootstock. Having said this, in a nursery situation, it is often hard to catch those escapes that are outcrosses, and for those nurseries that use seeds to propagate ‘Flordaguard’ rootstock, outcrosses occur approximately 5% of the time, with another 10-15% being rogued out due to slow growth or small diameter caliper.
Unfortunately at this point, we don’t have any good solutions other than planting our varieties on nematode-resistant rootstocks, like ‘Flordaguard’. We have an ongoing project to figure out why ‘Flordaguard’ is resistant, as well as evaluating other rootstocks that may be resistant from the USDA-ARS Peach Rootstock Breeding program in Byron, GA. In many cases, fumigation may work – and we have a separate project to examine the effectiveness of the recommended rate as well as a half-rate of Telone II as a pre-plant fumigant in reducing the impact of peach root-knot nematode.
If you would like to submit a nematode sampling for identification, please send a sample to the UF Nematode Assay Lab – http://edis.ifas.ufl.edu/sr011. As always, please contact either myself or your local county extension agent regarding orchard issues. We are always here to help!