Huitlacoche Production as an Alternative Crop in South Texas

Huitlacoche Production as an Alternative Crop in South Texas

Summary

Research to develop reliable propagation techniques for the commercial production of huitlacoche has produced one promising method. Silk-channel inoculation is the only technique that produced huitlacoche, but only those ears inoculated with a pure culture strain of Ustilago maydis (the fungus that causes huitlacoche to develop in corn) produced huitlacoche in a substantial quantity. Corn cultivar may also play a role in the quantity of huitlacoche produced.

Objectives/Performance Targets

For huitlacoche to be a dependable crop, propagation must be deliberate, as opposed to gathering the wild product opportunistically. This research project will determine whether huitlacoche can be commercially propagated in South Texas, in weather conditions typical throughout the South.

This research project includes the following objectives:

1. Determine what sources of huitlacoche spores provide the highest success rate for propagation.

In order to inoculate corn, huitlacoche spores must be gathered. Sources of huitlacoche spores will include frozen huitlacoche, fresh huitlacoche, and pure culture strains of Ustilago maydis, the fungus that causes huitlacoche to develop in corn. Frozen huitlacoche will be purchased from an online source, and fresh huitlacoche will be culled from naturally occurring huitlacoche in corn fields. Pure culture strains of U. maydis will be obtained from researchers at the University of Illinois. A sporidial suspension will be produced with each of these sources and used to inoculate corn in order to determine its viability as an inoculum. Percentage of corn in which huitlacoche develops will be evaluated. If it is determined in the first year of this project that one of these spore sources is not a viable candidate for huitlacoche production (produces no huitlacoche), it will be dropped from the trial and the focus will shift to the source(s) that remains. The steps involved in determining the best spore source for huitlacoche propagation include:

a. Investigate and collect possible sources of huitlacoche spores.
b. Create and maintain sporidial suspensions with each spore source.
c. Inoculate corn using each spore source.
d. Assess percentage of corn in which huitlacoche develops.

2. Determine what varieties of corn are best suited for huitlacoche propagation.

Some varieties of corn may be more prone to developing huitlacoche than others. To determine which varieties are best suited for huitlacoche production in South Texas weather conditions, three varieties identified as being suitable for huitlacoche production will be planted and inoculated with each of the spore sources previously described. The trials will be conducted through four growing seasons (spring and fall 2013 and spring and fall 2014). Steps required to determine which varieties of corn are most suitable for huitlacoche production include:

a. Plant three corn varieties that research has shown are the most appropriate for huitlacoche propagation.
b. Inoculate each variety with each spore source.
c. Evaluate the number of plants and ears that produced huitlacoche in each variety.

3. Determine what propagation techniques result in the highest propagation success rates.

Records indicate that the ancient Aztecs would purposely injure corn plants by making cuts at the base of the plants in order to give naturally occurring huitlacoche spores an avenue into the vascular system of the plant and thus effectively propagating the fungus. More recently, attempts at huitlacoche propagation involve injecting spores directly into the silk channel of each ear of corn. It has also recently been shown that pollination inhibits the propagation of huitlacoche, so in order to increase propagation success, pollination must be prevented by removing the pollen-containing corn tassels. Using the three sources of spores (frozen, fresh, and pure culture), three techniques will be used to inoculate the corn. They include injecting sporidial suspensions down the silk channel of each ear, injuring the base of the cornstalk of young plants and spraying the suspensions on the abraded tissue, and injecting sporidial suspensions into the leaf swirl of the developing corn plant. It will be determined which of these techniques results in a higher incidence of huitlacoche development. Control plants will not be inoculated to determine the rate of natural infection. Steps required to identify methods that consistently induce the formation of huitlacoche in corn include:

a. Remove tassels from all corn plants to prevent pollination.
b. Inoculate corn using traditional (Aztec) and modern methods for huitlacoche propagation.
c. Record incidence of huitlacoche for each method.

4. Disseminate findings to local growers through outreach efforts.

A major objective of this Research Project is to share the knowledge gained with small-scale producers in the South so that they may be able to grow this alternative crop and sell it for a premium price through direct-marketing channels. Outreach efforts will begin by reporting results on the University’s outreach website, and continue with the production and broadcasting of a project video. The project video will be produced and broadcast on a regional television station by Valley Telephone Cooperative. The University also operates a number of USDA-funded outreach projects that will provide effective outreach for project research. Training events will be conducted by the University and its resource partners, including University outreach projects funded by USDA Office of Advocacy and Outreach (OAO), National Institute of Food and Agriculture (NIFA), and Natural Resources Conservation Service (NRCS). During the training events, growers will be informed of the best spore source, corn variety, and inoculation technique to use in order to grow huitlacoche successfully. Instructions and demonstrations will be presented on how to create the sporidial suspensions and how to inoculate the corn. The steps required to fulfill this objective include:

a. Create a report for the University website and update it as findings become available.
b. Produce a video detailing the Project and all of its components.
c. Broadcast the video on a regional television station.
d. Conduct training events for local growers.

Accomplishments/Milestones

Trials were conducted in the spring, summer, and fall of 2013 at a cooperator farm near Lyford, Texas. The spring and fall trials tested three inoculation techniques, three types of huitlacoche spores/inoculum, and three corn cultivars. The summer trial was an abbreviated trial in which only one cultivar of corn was tested instead of three. Inoculation technique and inoculum type played a significant role in the development of huitlacoche, while the role corn cultivar plays in the development of huitlacoche has yet to be determined.

Three types of inoculum were tested in all three trials, each using a different source of Ustilago maydis, the fungus that causes huitlacoche to develop in corn. The first inoculum was created by drying and grinding fresh huitlacoche galls gathered from an area corn field in the fall of 2012 and mixing the resulting powder with water immediately before use. The second inoculum was created by blending frozen huitlacoche galls purchased from an online source with water immediately before use. The third inoculum was prepared by combining two pure-culture strains of U. maydis and growing them in a nutrient broth. Only a few incidental huitlacoche galls developed in ears inoculated with either the dried or frozen galls. The corn inoculated with the pure culture strain are the only ones in which a substantial amount of huitlacoche developed, but only in the spring trial.

The same methods were used to grow the pure strains of U. maydis fungus in a nutrient broth for the summer and fall trials, but no huitlacoche developed in these two trials. The most likely explanation is that the two pure cultures were no longer viable. These cultures are usually lyophilized (freeze-dried) and stored at -80°C, but the equipment needed to store the cultures this way was not available for this research project. Instead, the cultures were stored in a commercial refrigerator at 2°C. When the cultures were transferred to the nutrient broth, they were either dead or damaged enough to prevent them from growing when used during the summer and fall trials.

Each inoculum was applied to all corn cultivars using three different methods – abrading the corn stalk and applying the inoculum to the abraded tissue, injecting inoculum into the developing leaf swirl of the corn plants, and injecting the inoculum directly into the ears of corn (silk-channel inoculation). While huitlacoche galls developed with all inoculum types, they formed only in those ears inoculated via the silk channel, but the success rate differed depending on the corn cultivar. No huitlacoche developed in plants inoculated with the other two methods.

At this point in the research, it appears that corn cultivar may play a role in the development of huitlacoche in corn, but it has not been determined how big a role it plays. The corn cultivars tested were selected based on their lack of resistance to Ustilago maydis. These cultivars were Golden Bantam, Golden Beauty, Golden Jubilee, and Silver Queen. In the spring trial, Golden Bantam and Silver Queen cultivars produced huitlacoche at the nearly the same rate when inoculated with the pure culture strain of U. maydis via the silk channel (61% and 58%, respectively, of ears inoculated produced huitlacoche), and both cultivars grew well in the weather conditions of South Texas. Golden Beauty, however, exhibited stunted growth and poor ear and huitlacoche development (18% success rate). This cultivar cannot be recommended for the commercial production of huitlacoche in South Texas and was replaced with Golden Jubilee in the fall. Since no huitlacoche developed in any of the cultivars in the fall 2013 trial, no determination can be made about Golden Jubilee cultivar regarding its susceptibility to the huitlacoche fungus. It did, however, grow very well and exhibited excellent ear development.

The amount of huitlacoche produced did differ between Golden Bantam and Silver Queen cultivars. Because so few ears developed huitlacoche in Golden Beauty cultivar (18% success rate), less than one-half pound of huitlacoche was harvested, and so it will not be evaluated further. Golden Bantam produced an average of 0.2 pounds of huitlacoche per ear of corn, but a 3.5 inch rain event two days before the harvest of the huitlacoche growing on the Silver Queen cultivar made the galls wet and sloppy, and therefore they could not be weighed accurately. Instead, the percentage of the ear in which huitlacoche galls were growing instead of kernels was recorded.

Of the ears that developed huitlacoche, 33% of Golden Bantam and 60% of Silver Queen had over three-quarters of the kernels replaced by huitlacoche galls. Ten percent of Golden Bantam and 7% of Silver Queen had between one-half and three-quarters of the kernels replaced by huitlacoche galls. Fifty-seven percent of Golden Bantam and 36% of Silver Queen had less than half of the ear growing huitlacoche.

To summarize, the only method that produced huitlacoche in a substantial quantity was injecting the pure culture of Ustilago maydis directly into the corn ears. The different corn cultivars did produce various amounts of huitlacoche, but with only one successful trial, it is difficult to assess the role that corn cultivar plays in the development of huitlacoche. Additional research is needed to determine if certain corn cultivars are indeed more susceptible to the huitlacoche fungus or if some produce more huitlacoche than others, or if it is more a result of the technique of the person inoculating the corn. Some people may be more precise in their application, and this could be what is causing the difference in yield between the cultivars.

The most pressing concern at this stage in the research is to identify a way to keep the pure cultures of Ustilago maydis alive without storing them in a -80°C freezer. If a system can be devised, a grower would be able to easily adopt the most successful method for propagating huitlacoche thus far and use the same cultures from season to season. If a storage method cannot be developed, growers may have to rely on a biological supply company or laboratory to grow the cultures for them. The cost and feasibility of this has not been investigated.

While only a few galls of huitlacoche were produced with the inoculum created with both the dried and frozen galls, additional research is needed to definitively exclude them as viable sources for an inoculum. Using a pure culture of Ustilago maydis to create an inoculum is not a difficult process, but it does require specialized laboratory equipment that is not typically available to growers. In all three trials conducted so far, the dried and frozen spores were mixed with water immediately before use. Future trials could include incubating the spores in a nutrient broth for a number of days before being injected into the corn ears. If one of these sources is successful in producing huitlacoche, it would make the commercial production of huitlacoche much more accessible to a larger population of growers.

• Silk-Channel Inoculation – Pure Cutlure
• Huitlacoche2
• Huitlacoche1
• Leaf Swirl Inoculation
• Abraded Tissue Inoculation
• Silk-Channel Inoculation – Fresh Spores

Impacts and Contributions/Outcomes

Since its inception, this research has received positive attention both in the South and from across the nation. Two national agriculture magazines, Southwest Farm Press and Farm Show, have showcased the project. The articles in these magazines have garnered requests for more information from growers and future growers in Texas, Pennsylvania, and Missouri. These growers are extremely interested in growing huitlacoche to increase their farm profits. Efforts will be made to contact the growers when the research is complete, and to share with them the most viable method(s) for growing huitlacoche.

One unexpected request for information has come from a chef in Oklahoma City, Oklahoma, who serves huitlacoche dishes in his high-end restaurant but has been disappointed with the canned and frozen sources available. This chef was very eager to find a grower in Texas, or anywhere in the South, from which he could buy fresh huitlacoche.

Most recently, a tour of the cooperator farm was conducted in November 2013 during the USDA Beginning Farmer and Rancher Development (BFRD) Program’s annual conference. Twenty BFRD project directors from across the nation received an in-depth description of the project, including propagation methods being tested and the results thus far. A taste-testing of a huitlacoche dish followed the presentation.

The most comprehensive coverage of this research project has come from a video produced by VTXTV Channel 1, a regional television station providing television access to rural areas of South Texas. The video details the project’s goals and the methods being tested with a hands-on demonstration of each. This video has aired daily since November 2013, reaching between 1,000 and 3,000 subscribers.  The video is also available online at http://www.youtube.com/watch?v=0sv61gDXul0

The press generated by this project has farmers and chefs excited about the prospect of a new specialty crop that would allow them to increase their profits and economic sustainability by allowing them to charge premium prices for huitlacoche, which sells for a much higher price than the corn on which it grows. In the United States, huitlacoche has been gaining in popularity, thanks in part to the increasing Mexican American population and also because of American consumers’ new affinity for or willingness to try new and exotic foods. With increased product demand and a high market price, cultivation of huitlacoche has the potential to provide sustainable, small-scale growers enough income to increase their economic sustainability.

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