Allium white rot biostimulation project-Part 2
Our current Farmer Grant FNE13-782 is a continuation of FNE11-721, and is designed to continue studying biostimulation as a management tool for Allium White Rot (AWR). As AWR is particularly pernicious and can persist in affected soil for more than 20 years, we are approaching this study very seriously.
We are using two specific biostimulants – fresh garlic juice and ground healthy garlic plant material (and control beds receiving no treatment) – to stimulate growth of AWR sclerotia (resting fungal fruiting bodies). With no actual allium family plant for the fungal sclerotia to attach to, they will die, thus reducing the amount of pathogen in the soil.
The combination of the two Grants will span 4 years, the usual length of a crop rotation period in Organic Agriculture. At the end of the 4-year period (with additional biostimulation applications in both 2014 and 2015) we will plant spring onions (a crop which is also a biostimulant because of the short time in the soil) and storage onions, to assess how much of the pathogen has or has not been removed from the soil. We are using annual soil assays (from a lab in California, Nematodes, Inc.) of the fungal sclerotia to track and assess the progress.
Please refer to FNE11-721, 2011 Annual Report, for photos of our bed construction, application of biostimulants, sanitation protocols, and subsequent crops.
We continue to work with Dave Fuller and Dr. Steve Johnson, of the University of Maine Cooperative Extension, and Dr. Fred Crowe, Professor Emeritus, University of Oregon. As this is a continuing study with no essential changes in our method, we are keeping them up to speed, reporting in to them several times a year.
Our crops have not changed substantially. We continue to grow a large assortment of trial tomato varieties, basic mixed vegetables, herbs, and everlastings. As usual we’ve had to roll with the weather vagaries/challenges, but that seems to go along with it every year.
The most important continuing change(s) is our annual construction of new wooden sided raised beds. The new beds allow us to continue growing garlic for our value-added products. We are bringing in clean soil (from a nearby Certified Organic farm) to fill these boxes. We will build 5-6 more boxes in each 2014 and 2015, finally allowing us a full 4-year rotation for garlic and other allium crops.
We are continuing to respect strict sanitation rules to prevent any and all spread of the disease. This includes rotational grazing for our layers.
One challenge is that our raised beds are wooden sided, and in the natural course of things some parts deteriorate. We have inserted re-rod stakes to support the sides of the beds in the SARE study, and will continue to do that where and when necessary.
We are actually between seasons at this point (December 2013). This past fall we completed harvesting from the SARE beds. The 2013 crop was popcorn! We prepped and added soil amendments (rock powders, etc) and mulched the beds in preparation for 2014. We are taking care to observe sanitation rules, including washing of all tools, equipment, hands, and gloves, to prevent moving the disease from bed to bed. In 2013 we planted all aboveground crops in the SARE beds, making harvest and fall cleanup easier.
In the spring, in late May or early June, we will take soil samples to send off for the assay of AWR sclerotia.
We have accumulated three assays so far – 2011, 2012, and 2013 – and these are showing improvement. Assays from 2014 and 2015 should provide enough data, over a long enough period, to iron out some variables we have discovered. The prime variable is that we simply cannot dig in enough places or at the same depths, for every sample. And, given the variations in spring weather patterns from year-to-year, we’ve not managed to take samples with near to same soil temperatures. Again, we hope that 5 years of sampling will be sufficient.
In 2015 we will do a test planting of long and short term allium crops to assess how much of the pathogen we have removed.
We are continuing to gather data from the soil assays of AWR sclerotia. We are tracking significant improvement, and will be looking to the 2014 and 2015 results to complete the assessment of the potential of biostimulation as an AWR management tool.
As we have both returning and new help every year, training continues to be very important. Because of the nature of AWR, a complete understanding of the dangers of moving the pathogen cannot be stressed enough. We review the necessary sanitation measures, every time, before setting foot or tool in any garden area.
We are on track so far! Since the beginning of our first grant, FNE11-721, we’ve been able to streamline a lot, and hopefully we will be able to continue making the process easier. The soil prep, applications of biostimulants, and sanitation protocols are becoming routine, but we are very aware of the danger of becoming casual.
Impacts and Contributions/Outcomes
UMaine Cooperative Extension
138 Pleasant Street
Farmington, ME 04938-5828
Office Phone: 2077784650