2016:11
HRI Launches New Fund in Honor of Craig Regelbrugge In 2015, Craig Regelbrugge celebrated his 25th year of service to our great industry. Craig advocates for horticulture every day. Now it’s our turn to be advocates for horticulture and honor Craig at the same time. Many of us have enjoyed and profited from Craig’s efforts over the years. Many of us have had the privilege of assisting Craig’s work, while many more of us have often been the beneficiaries of his knowledge and insights. He’s spoken at countless green industry events, sharing his knowledge of the critical role regulations and laws have on our collective business success—knowledge that is increasingly important for our teams to have.
Craig has inspired many of us to pay better attention to the nuances of the ever-changing political landscape and he’s guided our industry through some tumultuous terrains. He’s spent tens of thousands of hours advocating for our interests and thousands more educating us. Please join us and contribute to this special HRI fund in honor of Craig and the remarkable opportunities horticulture has given to so many of us. Make a donation today! Donate online at AmericanHort.org, at HRIResearch.org, or by contacting Jennifer Gray at 614-884-1155, JenniferG@AmericanHort.org.
What’s Inside:
In honor of Craig’s extraordinary contributions to the horticultural industry, a group of AmericanHort and Horticultural Research Institute friends conceived of a plan to create a special HRI endowment fund in Craig’s name. In addition to providing needed funding for horticultural research, this fund allows us to publicly acknowledge our gratitude for Craig and the work he has thoughtfully undertaken on our behalf. We thoroughly surprised Craig and announced this fund at the HRI reception at Cultivate’16. Through the remarkable generosity of many donors, Craig’s fund quickly exceeded $35,000 in pledges.
HRI Launches New Fund in Honor of Craig Regelbrugge
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The Story Behind San Francisco’s First Community-Built Living Wall, and the Woman Behind It
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Three Steps to Landing Larger Floral Clients
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Basics & Applications of Vegetable Grafting
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Our goal is to get the “Craig Regelbrugge— Advocates for Horticulture Fund” to $52,000 before Craig’s 52nd birthday in November. Will you help us get there?
Seeking Passionate People to Guide, Support, and Lead the Industry
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Macronutrient Deficiencies
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Connect: An AmericanHort Member Benefit
Business Solutions Organized for Your Business Interests The AmericanHort Knowledge Center is your go-to-resource for information you and your employees need. Visit AmericanHort.org/Connect for more business-building solutions.
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over 1,200 square feet, this living canvas not only provides a beautifully refreshing treat for the senses, but also creates a thriving habitat for nature, attracting birds, butterflies and bees into the city— and bringing new life and cleaner air to community citizens. What also makes this wall unique is that it’s built to be self-sustaining, incorporating a complex vertical irrigation system that includes over 200 feet of irrigation and a 1,350-gallon recirculating rain catchment tank.
By Amanda Goldberg
For most, this installation, which was planted in a matter of only six days, seemed to have magically appeared overnight and many have wondered about who built it. The beauty is that it was not just one person, but a community of close to 100 helping hands spearheaded by passionate plant-lover and ecological designer, Amanda Goldberg, the founder of Planted Design (planteddesign.com). “From our clients, who rolled up their sleeves to help out and invited their friends and family to do the same, to people passing by who volunteered to wrap the roots of a plant, to my amazing codesigner, Brandon Pruett, and other experts who lent their wisdom to this project—this was truly a community collaboration. I feel honored to have the opportunity to lead this project and bring it all together,” comments Goldberg. Goldberg launched Planted Design in 2014 with the dream of bringing the beauty and health benefits of nature back into the city by transforming otherwise lifeless walls and spaces into living and green forms of art, most of which can thrive without much, or any, help. With a Masters in Regenerative Design from Cal Poly Pomona and a resume that includes working with Cradle to Cradle Institute, presenting to the US Green Building Council and a LEED accreditation, she is well-suited to take on this goal. Already, her list of clients has included Twitter, Go Raw, Living Intentions, Caliva and Ann Marie Giovanni Organic Cosmetics.
Amid the concrete, industrial jungle of San Francisco’s Mission District, rising up 30 feet to the sky on 14th Street and Van Ness, there is a mural unlike any other in the area…a living, breathing, evolving work of art. 2 | AmericanHort.org
Instead of spray paint, used in much of the artwork in the Mission, this building is covered with a colorful, fragrant compilation of more than 3,200 droughtresistant plants, many of which are also native species. Woven together artistically and intentionally
Local residents also appreciate the new installation. Becca Sherman, who has lived in the area for 11 years, comments, “I can’t help but smile when I walk by. It makes the block come alive with beauty. Instead of looking down at the pavement, we look up to see the plants flourishing from sidewalk to sky.”
What’s on the wall? Since the Mission District is one of the hottest, driest microclimates in the city—and and given California’s current draught—plants were chosen based on their ability to survive with low water and full sun and wind exposure, as well as their visual and olfactory appeal. The way the plants were combined, however, is where the true green genius comes into play.
Who’s behind the wall?
The Story Behind San Francisco’s First Community-Built Living Wall, and the Woman Behind It
workspace or giving life to a community wall, like the one we just built.”
“As humans, most of us now spend 90 percent of our life surrounded by walls or commuting in a maze of concrete and metal, yet we all have an intrinsic need to connect with nature,” says Goldberg. “When we’re around plants we literally breathe easier. Planted Design’s clients also see the value of plants, whether it’s greening an indoor
“As the ‘plant people’ on this project, Amanda and I were tasked with not only finding plants that visually go together, but also bringing together plants that can grow together,” says co-designer, Pruett, who also works with Living Green Designs. Pruett also points out that the wall was designed to stimulate all the senses. For example the Yerba Buena, a native trailing plant with little white flowers that smell like mint, was placed right over the entry so that when people walk into the building and brush up against the plant, they release a refreshing scent. Another area of the wall, called “The Meadow,” has varying heights of plants, including tall native grasses, short grasses with blooming flowers, as well as bonsai-sized pine trees where birds have already began nesting.
Visually, this living wall will be ever-evolving. If you see it during a sunny day, the blossoms of the delosperma, commonly called the ice plant, will be fully open, while at night or on cloudy days they will be closed. “It will also change with the seasons. When one plant dies others will bloom and have their time to shine.” comments Goldberg. “We hope this wall inspires more communities and likeminded businesses to support the creation of living walls such as this so we can help bring new life and vitality to cities.”
Amanda Goldberg Planted Design amanda@planteddesign.com Editor’s note: Planted Design won a Platinum Award in the Design Category of AmericanHort’s 2016 International Plantscape Awards. To learn morning information about the contest, visit AmericanHort.org/Plantscape. 2016:11 | 3
Three Steps to Landing Larger Floral Clients
Basics & Applications of Vegetable Grafting
By Joy Gendusa
By Chieri Kubota
You can get by as a florist selling to individuals and wedding parties, but there are bigger fish to fry in your pond if you have the drive and marketing savvy to land them. I’m talking about businesses like hotels, restaurants, etc. Many businesses, including hotels and restaurants, use fresh flowers to add atmosphere to their space. Think about it: they have to get those flowers from somewhere. Why not your business?
But how do you write a USP? Here’s a tip: “We’re better,” isn’t a USP. “We are the ONLY florist in the Denver area that offers FREE arrangements with orders over $500,” is a great USP. It needs to be specific and show how you are different and better than your competitors. You may have to change the way you currently do business in order to differentiate yourself and be able to be unique in a crowded space. Your USP needs to be front and center on your postcard. You may only have a few seconds to make an impression on your prospect and you want the USP to be that impression.
Follow Up Follow up is an absolutely critical part of your marketing strategy. Without it, you can kiss 75 percent of your potential sales goodbye. E-mail is a fantastic way to follow up because it is cheap. Postcards bring in the leads and e-mail helps you to close them.
Here are the three steps to landing larger floral clients: Get Their Attention Getting the attention of larger businesses can be tricky. These kinds of businesses receive tons of advertisements every day, which means a 4”x6” postcard won’t cut it for this type of promotion. You may have to go bigger. Many postcard marketing companies offer larger sized cards for just this reason. In addition, you are going to need a very specific mailing list. This list should target the businesses in your area that are most likely to respond to your offer. Consider targeting only hotels and restaurants of a certain size to start off with. Then, someday you will be able to mail to every hotel and restaurant in your area.
Communicate Your Unique Selling Proposition Attention all by itself won’t get you anything. That’s where a laser-focused unique selling proposition (USP) comes in. A USP is a short statement about why a company should choose your florist business over a competing business. 4 | AmericanHort.org
You want to have a series of e-mails you can send to your prospects that explain how you can meet their flower needs and why your business is better suited to do so than anyone else’s. This type of e-mail series is called an “autoresponder” because it goes out automatically when you enter the prospect’s contact info. In addition to following up with e-mails, it wouldn’t hurt to call or visit the businesses you really want to land to talk to someone who is in a position to make a decision. The personal attention shows that you are serious about partnering with them and that you care about their business. Even if you don’t land these businesses’ contracts right away, the more you target them, the more you build your company’s name in the mind of your prospects. That means the next time their current provider fails them, you are the first call they make.
Joy Gendusa Founder and CEO, PostcardMania postcardmania.com | 800-628-1804 2145 Sunnydale Blvd., Clearwater, FL 33765 joy.gendusa@postcardmania.com
Introduction—A bit of history
the first North American operation in the U.S. Considering the large acreage used for fruiting vegetable production in the U.S. it seems that potential market of grafted vegetable plants is much larger than what only a small number of nursery operations can possibly serve, if this technology makes sense and is economically feasible in various regional production systems. Watermelon has been a major crop species worldwide for which grafting was introduced to control fusarium so that production can remain in the same field every year. In Mexico, as well as U.S. we are beginning to see the application of grafting in commercial fields where fumigation or crop rotation is becoming more challenging. Perhaps vegetable grafting can be something worth considering for plug and bedding plant growers, as there are common infrastructures that can be shared with the existing crops. The following is a brief review of the practices.
Vegetable grafting has been practiced for many years worldwide. The oldest record reportedly exists in China during the 5th Century, with regard to grafting gourd plants to increase fruit size (Lee and Oda, 2003). The use of grafting for pest and disease management was not practiced until the 20th Century when more intensive vegetable cultivation began, supporting growing economies and food demands. One such record was in the late 1920s when a watermelon grower in Akashi, Japan demonstrated that he could grow watermelon in a field infested with fusarium, when grafted onto resistant squash. This was reported by a regional researcher who, in the extension article, called for the national need of further studying vegetable grafting as a potential technology for sustainable vegetable crop production (Tateishi, 1927). Today, many commercial rootstocks are available for various fruiting vegetables including cucumber, eggplant, melon, pepper, tomato and watermelon and Selecting rootstocks billions of vegetable plants are grafted worldwide ‘So which rootstock should I use?’—This is to overcome soil borne disease, increase overall a typical question that we receive from both yield, improve fruit quality as well as endure harsh nurseries and growers who are producing or climate or growing conditions. In North America, using grafted plants for the first time. Unless use of grafting was first advanced they are for the retail market, in Canada, nurseries should following the communicate with preceding the users (the Dutch customers who grow growers who the plants to harvest introduced fruit, i.e. growers) to grafting as part of define the objective key technologies of the grafting (yield to increase yields increase, specific in greenhouse disease control or tomato both) and then production. communicate with Similarly, in the seed companies Mexico grafting to select the was introduced along rootstock that will Figure 1. Tomato grafted plants pinched to induce with the rapid most likely meet two axillary shoots arrived at a greenhouse in development of the expectations. Arizona after travelling thousands of miles. tomato industry. Commercial Both countries have rootstock several large scale information has been updated and available at grafting nurseries producing millions of grafted a USDA-funded vegetable grafting information plants annually. Because importation of tomato website (vegetablegrafting.org). In most cases, plants from Mexico is prohibited in the U.S., the ‘which scion should I use’ is not a question since Figure 1. Tomato grafted plants pinched to induce two Canadian nurseries have been the only source axillary shoots arrived at a greenhouse in Arizona after users (growers) know what scion (variety) that of grafted plants until recently for U.S. growers travelling thousands of miles they want to grow. Grafting is typically used to (Kubota et al., 2008). More recently, nurseries in complement traits missing in the scion variety. the U.S. began grafting vegetables and a large Therefore, the task is always to select the best international nursery announced their plan to build more on page 6… 2016:11 | 5
Basics & Applications of Vegetable Grafting… continued from page 5 matching rootstock that meets the expectation of growers. It is important to understand that the efficacy of grafting depends on the crop production conditions. When plants experience little abiotic or biotic stress and are growing under optimum environments, the obvious benefit of grafting may be minimal.
Figure 2. Grafted watermelon seedlings. After healing, cuttings can be excised to pack for longdistance distribution.
Scheduling scion and rootstock seedling production Once candidate rootstocks are decided, the next critical task at a grafting nursery is to determine the propagation schedule that includes seeding/ germination, pre-grafting, healing, and finishing/ hardening stages. Most widely practiced grafting techniques (tube grafting for tomato, and one cotyledon grafting for watermelon; see Vegetablegrafting.org website for further information) require matching stem size between scion and rootstock seedlings. Some rootstocks may need more days than scion varieties to grow, or vice versa. Graftable stage for tomato and its rootstock is typically at a 1.5 true-leaf stage, which is often reached 14–21 days after seeding. Graftable stage for watermelon and its rootstock is typically at cotyledonary stage, which may be 8–12 days after seeding. Cell density can be also selected so that the plant size can be effectively controlled. Generally the higher the density is, the thinner and smaller in size the plants become. A short-term storage of scion and rootstock plants at selected low temperature may be another effective tool to slow down the fast growing plants to synchronize size. However temperature and light irradiance needs to be selected depending on the species (Spalholz, 2013).
Grafting also does not control foliar disease or pests and so it is a partial protection relative to the wide range of pathogens that exist in production fields. However, when the rootstock can control a disease to which scion varieties are susceptible, and when Figure 2. Grafted watermelon seedlings. After healing, the disease exists in the field where grafting is to cuttings can be excised to pack for long‐distance be used, the impact of grafting is often huge. In distribution. hydroponic greenhouse, where soil-borne disease is not a typical concern, grafting is used to enhance the yield of tomato by introducing a vigorous rootstock that can sustain the long production cycle Figure 3. Commercial indoor healing system (as long as 10–12 months). A typical increase in developed based on surplus shipping container. yield by grafting in such hydroponic greenhouses is 10–15%, which more than accounts for the For grafting, most nurseries use manual grafting as it costs of grafted seedlings in such highly intensive is the most flexible method to graft plants especially greenhouse production (average tomato yield when plant size is not uniform. Grafters need to find of modern varieties is 60 kg m-2; Higashide and matching scion and rootstock plants based on the stem Heuvelink, 2009). Because of the strong rootstock, size. To accelerate the process, there are varieties of greenhouse growers are also able to use grafted automation developed for grafting nurseries, including plants with two stems (Figure1) to reduce the sorting machine and grafting robots. Grafting robots number of plants while maintaining the same stem are designed to replace human workers engaged in (vine) density inside the greenhouse and per-stem some of the critical tasks of grafting nurseries. The yields, which further reduces the relative costs of most recent technology development was for tomato using grafted plants. Under much less controlled grafting and the fastest machines would achieve environment (such as high tunnel) the increase in approximately 1000 grafts per hour with one or yield achieved by grafting could be greater than the two workers assisting the machine (ISO Group, the greenhouse benchmark increase, but depends on Netherlands). Manual grafting speeds vary between the conditions and the rootstocks used. This is why Figure 3. Commercial indoor healing system developed based 100 to 400 grafts per hour depending on the it is recommended to test multiple rootstocks when on surplus shipping container. grafting methods, worker’s skills, plant uniformity, as you are using grafted plants as a potential solution to well as the overall logistics of design of the grafting address your problem (low yield or disease). Also, it is department at the nursery. Order size also affects the critical to use high quality grafted plants produced by grafting efficiency. Dealing with larger orders of fewer experienced nurseries, as the quality of grafts largely combinations of scion and rootstock is more efficient affects the performance of grafted plants. than many orders of various combinations. For further information, the cost analyses of grafting nurseries at 6 | AmericanHort.org
different technology levels and production sizes are reported (Lewis et al., 2014).
Healing your grafts to take Immediately after grafting is done, plants need to be placed inside an ‘intensive care facility’. This stage is called ‘healing’ because it heals the wounds and lets the new vascular system develop to connect the two different tissues (scion and rootstock).
Many grafting beginners fail in this stage by overlooking the importance of environmental control, ending up with low success rates or with poor quality grafts that would not perform well after transplanting. When the grafting is correctly done and the healing environmental conditions are controlled at optimum levels, your grafts are well healed and will not wilt when plants are returned to the nursery greenhouse. Table 1 lists some key tips of successful healing.
Table 1: Tips of Successful Healing 1. Recommended conditions. a. Durations: 5 days for tomato, 7 days for cucurbit when the conditions are optimum. b. Relative humidity at 95% or greater for the first 3–4 days and then gradually decrease towards the end of healing (5th -7th days). c. Air temperature at 28–29C (82-84F) for the first 4–5 days and then gradually lower to the ambient level towards the end of healing. d. Continuous lighting at 50–100 µmol m-2 s-1 photosynthetic photon flux (PPF) (300 to 700 foot candle depending on the light source) to prevent stretching/yellowing and to provide minimum photosynthetic energy to balance the loss by respiration. Two fluorescent lamps over each 2-foot wide shelf of the same length can achieve this target irradiance. First 24 hours can be under darkness. 2. Design a chamber that can consistently create the required environments. In commercial nurseries, renovating surplus shipping containers or trailers (Figure 3) is typical option as well as building bench-top tunnels inside a controlled environment greenhouse (Figure 4). Use of indoor facility with electric lighting is generally preferred because environmental conditions inside such a system are independent from the outdoor weather conditions. If the healing condition is not optimum, a longer duration will be required to get completely healed grafted unions or the survival rate will be low. 3. When plants are kept in the near saturated humidity for a prolonged period of time beyond the critical stage of first 3-4 days, plants tend to stretch or produce adventitious roots. However, these aerial roots usually die after removal from humid chamber. 4. Frequent sanitation and cleaning of the entire healing system are highly recommended to minimize the introduction of fungal diseases during healing. 5. For tomato, limit the irrigation for rootstock plants before grafting. Vigorous rootstocks sometimes create too high root pressure and prevent complete contact at the grafted union, preventing plants from developing connecting vascular systems. When this is the case, the graft unions are only partially healed or not strong enough and easily detached even after 7 days of healing in optimum healing conditions.
Unique applications of grafting One of the unique technologies developed recently is the use of grafted cuttings for distribution over long distance with minimum costs of packing and shipping. Large nurseries overseas recently started using this technology to distribute the high quality grafted plant materials to countries which do not yet have sizable commercial grafting operations. This is exactly the same type of business model as the use of unrooted cuttings for ornamental plants shipped from the nurseries overseas. However, in the U.S. this international distribution of grafted materials is currently limited to cucurbits as there is importation restriction of live tomato plants due to a virus outbreak and tomato is one of the host plants (USDA, 2009). Grafted cuttings are harvested after completion of healing and shipped long distance (Figure 2). Local propagators receive the unrooted grafted cuttings and root them under high humidity and shading, followed by standard hardening/finishing stage.
Grafting old varieties such as heirlooms onto modern rootstocks is a unique application that became popular in the U.S. Heirloom varieties generally do not have any resistances to any major diseases. Grafting onto modern rootstock varieties may add vigor as well as disease resistance. One caveat is a possible incompatibility of tomato grafting, originating from the genetic type of ToMV resistance of rootstocks. Nurseries and growers are recommended to communicate with academic scientists who understand the issue in order to make proper selections of rootstocks used for heirloom tomato. Grafting two or more different varieties (or species) onto the same rootstock has been practiced as a demonstration at an agricultural expo, grafting tomato, eggplant and pepino onto tomato or eggplant rootstock (Oda, 1990). This multiple grafting has been also practiced in the home gardening grafting market in the U.S. as well as Europe. more on page 8… 2016:11 | 7
Basics & Applications of Vegetable Grafting… continued from page 7
Macronutrient Deficiencies By Cladio Pasian
Seeking Passionate People to Guide, Support, and Lead the Industry The AmericanHort Board of Directors are the people behind the plants who share both time and talent to help the industry grow, evolve, innovate, and prepare for the best future possible. Will you help move the horticulture industry forward? Apply to be on the AmericanHort Board of Directors and help unite and strengthen horticulture businesses across the country. Application deadline is November 22. Visit AmericanHort.org/Elections to learn more.
What does it mean to be a member of the board? Board of Director applications are reviewed and nominated by the Leadership Committee. Nominees are then voted on by AmericanHort member businesses. Members of the board serve threeyear terms and meet several times throughout the year. This group of passionate leaders are responsible for governing the direction and activities of AmericanHort, whose mission it is to serve and strengthen industry businesses.
Questions? Please contact Dale Deppe, Immediate Past Chairman of the Board at dale@springmeadownursery.com.
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Micronutrient disorders are the fertility problems that I see most often while visiting growers as an Extension Specialist (Figures 1 and 2). Micronutrients (from the Greek Micro=small and nutrient=nutritive) are mineral elements needed by plants in small quantities. Small variations from the optimum level required for plant growth can be damaging. By the
same token, levels slightly above those required for good growth can be toxic. It is very important for growers to have a clear understanding about micronutrient management. This article is a brief overview of the principles that control the availability of micronutrients in soilless mixes and how to correct imbalances.
Figure 1. Typical iron deficiency symptoms on Streptocarpella. Please, note that the symptoms manifest on young leaves.
Figure 2. Typical iron-manganese toxicity symptoms on Geranium.
Deficiency or Toxicity?
Nutrient Availability
A micronutrient disorder may be a deficiency (when the micronutrient is in deficit) or a toxicity (when the micronutrient is in excess). Deficiencies can occur either because the nutrients are not present in the growing mix or because the nutrient is present but unavailable to the plant. (Occasionally, plants with roots damaged by Pythium or other pathogens may show micronutrient deficiency symptoms.) Some commercially prepared mixes have a fertilizer charge that may include micronutrients. Growers preparing their own mixes should use one of the many commercially available micronutrient complexes to ensure that the micronutrients are present in the growing mix.
Sometimes, the micronutrient present in a growing mix is not available to the plant (the plant cannot take it up). Micronutrient availability is influenced by media pH: except for molybdenum, the availability of micronutrients decreases with increasing media pH and vice versa. Water alkalinity is an important factor modifying media pH and hence micronutrient availability. It is important to maintain the pH for soilless media between 5.5 and 6.3. Some crops are more sensitive to media pH than others: petunias and gerberas must be maintained at pH levels of 5.5 in order to avoid micronutrient deficiency symptoms. Other crops are more tolerant of pH changes. Table 1 shows the minimum and maximum critical foliar levels for floral crops.
Figure 4. Bench top tunnels inside nursery greenhouse to heal the grafted plants.
Further resources At the beginning of this Century, in North America, use of vegetable grafting was limited to greenhouse hydroponic tomato growers and not many growers or gardeners were aware of the technology. It was considered as a technology used only in unique cases Figure 4. Bench top tunnels inside nursery greenhouse to heal the by growers in the Far East. As research groups start grafted plants. making efforts to advance this potential technology development, and many ventures and new graftingrelated projects are being launched in North America, vegetable grafting has become known as a potentially effective IPM tool in vegetable crops in greenhouses, high tunnels, as well as open-fields. Now much information is available, after much research and extension effort throughout the nation. The online version of this article lists the websites where various information is available. Visit AmericanHort.org/KC to view the online version of this article
Chieri Kubota School of Plant Sciences The University of Arizona ckubota@email.arizona.edu References Higashide, T. and E. Heuvelink. 2009. Physiological and morphological changes over the past 50 years in yield components in tomato. J. Amer. Soc. Hort. Sci. 134:460-465. Kubota, C., M.A. McClure, N. Kokalis-Burelle, M.G. Bausher, and E.N. Rosskopf. 2008. Vegetable Grafting: History, Use, and Current Technology Status in North America. HortScience. 43:1664-1669. Lee, J.M. and M. Oda. 2003. Grafting of herbaceous vegetable and ornamental crops. In: Janick, J. (Ed.), Horticultural Review. John Wiley & Sons, New York, p. 61-124. Lewis, M., C. Kubota, R. Tronstad, and Y.-J. Son. 2014. Scenario-based cost analysis for vegetable grafting nurseries of different technology and size. HortScience 49:917-930. Oda, M. 1990. Grafted plant ‘Tomapena’ produces three different kinds of fruit in one plant. Japan Tobacco Plant Research Institute, Tochigi, Japan. 108pp. Spalholz, H. 2013. Development of short term storage techniques for grafted vegetable seedlings. Master thesis, the University of Arizona. 143pp. Tateishi, K. 1927. Grafting watermelon onto pumpkin. Japanese Journal of Horticulture (Nihon-Engei Zasshi). 39:5-8 [English translation is available at http://cals.arizona.edu/grafting] USDA APHIS. 2009. Federal order for tomato torrado virus and tomato severe leaf curl virus. USDA http://www.aphis.usda.gov/import_export/ plants/plant_imports/federal_order/downloads/tomato_viruses.pdf
Table 1. General critical foliar ranges for floral crops. (After J. Biernbaum, Water, growing media fertilizer, and root zone management. OFA Short Course, July 1994.) Nutrient
Minimum ppm
Maximum ppm
Iron (Fe)
50
Manganese (Mn)
30
500
Zinc (Zn)
20
100–200
Copper (Cu)
?
5
20–100
Boron (Bo)
25
100-300
Molybdenum (Mo)
0.5
15
Substrate pH If the deficiency is due to pH imbalance, the approach is to modify the pH of the mix. In this case, adding micronutrients can make matters worse because the level of individual micronutrients may
affect the level of other micronutrients in the plant through a process called antagonism. For example, too much iron may produce manganese and zinc deficiencies, while high levels of manganese may more on page 10… 2016:11 | 9
Macronutrient Deficiencies…continued from page 9 result in iron and zinc deficiencies. Copper and zinc are also antagonistic: too much of one may produce a deficiency of the other (Table 2). Nutrient Toxicity Toxicity on the other hand, can occur when micronutrients are applied in excess (usually more than one application). Common sources of micronutrients are: the charger in the mix and fertilizers applied during the crop cycle. Growers MUST have an idea of how much micronutrient they are adding through each of these sources in order
to avoid toxicities. Toxicity symptoms are difficult to recognize visually (only someone with a lot of experience can do it) and are usually mistaken by deficiency symptoms by growers. Correct Diagnosis How do we resolve these problems? First of all, only a correct diagnosis of the problem will lead to the proper solution. Do you have a micronutrient deficiency or is it an excess? Identify the micronutrient causing the problem. Identify the cause of the deficiency/toxicity: is the nutrient not present or is it present but unavailable? Answering these questions will help you (and your extension agent or consultant) tackle the problem.
Table 2. Availability of micronutrients as affected by other micronutrients (antagonism) and macronutrients in soilless mixes.
Toxicities are not easily corrected. The first step is stop adding the micronutrient that is in excess (switching to a fertilizer without the nutrient causing the problem). Slightly changing (raising, for most Micronutrients) the media pH will decrease the availability of all micronutrients (including the one in excess). Growers trying to correct a micronutrient
excess should raise the pH at the maximum level that the species/cultivar can tolerate for normal growth. Lastly, use antagonism as a tool: increase slightly the level of a micronutrient that will reduce the availability of another (e.g. if zinc is at high levels, slightly increase the level of copper).
Table 4. Sources, rates and micronutrient concentrations for a single corrective application of one or more micronutrients applied to the soil*. (After D.A. Bailey and P.V. Nelson, Managing micronutrients in the greenhouse. NCSU Extension, Leaflet No 553, 1991.) Micronutrient source
Weight of source per 100 gal (oz)
Concentration (ppm)
Iron sulfate--20% iron
4.0
62.0 Iron
Iron chelate (EDTA) — 12% iron
4.0
36.4 Iron
Manganese sulfate — 28% manganese
0.5
10.0 Manganese
Element
Availability reduced by:
Zinc sulfate — 36% zinc
0.5
13.9 Zinc
Boron
Organic nitrogenous fertilizers and high levels of phosphorus.
Copper sulfate — 25% copper
0.5
9.3 Copper
Manganese
High levels of potassium, phosphorus, iron, copper, and zinc.
Borax — 11% boron
0.75
6.25 Boron
Copper
High levels of zinc, nitrogen, and phosphorus
Iron
High levels of copper, manganese, zinc, and phosphorus.
Molybdenum
High levels of manganese and nitrate-nitrogen fertilizer.
Zinc
High levels of copper and phosphorus.
How to Correct the Problem If deficiency or toxicity are suspected, soil and foliar analysis are recommended for several reasons. First, visual identification of the problem is difficult in the absence of information (made available through analysis). Second, damage may be occurring that is not yet visible and by the time it becomes visible, the damage may be irreversible. Deficiencies can be corrected by adding the micronutrient that is in deficit or by correcting the factor that makes it unavailable (e.g. high pH). This
For soil-based media (>20% soil in media)
second course of action is very common among growers who have high alkalinity irrigation water. If only one micronutrient is deficient, DO NOT apply a micronutrient complex fertilizer because, as we mentioned above, imbalances can cause antagonism. Apply a salt that contains only the deficient micronutrient. Micronutrients can be I) added over time in small amounts with the irrigation water (Table 3); II) applied once with a concentrated solution during a normal watering (Table 4); III) applied as a single foliar spray.
Table 3. Sources, rates, and micronutrient concentration for continuous soil application of one or more micronutrients with every liquid fertilization. (After D.A. Bailey and P.V. Nelson, Managing micronutrients in the greenhouse. NCSU Extension, Leaflet No 553, 1991.) Micronutrient Source
Weight of Source per 100 gal (oz)
Concentration (ppm)
Iron sulfate--20% iron
0.13
2.00 Iron
Iron chelate (EDTA) — 12% iron
0.22
2.00 Iron
Manganese sulfate — 28% manganese
0.012 0.0018
0.05 Zinc
Copper sulfate — 25% copper
0.0027
0.05 Copper
0.030
0.25 Boron
Sodium molybdate -- 38% molybdemum
0.00035
0.01 Molybdemum
Ammonium molybdate — 54% molybdenum
0.00025
0.01 Molybdemum
10 | AmericanHort.org
0.027
0.77 Molybdemum
Ammonium molybdate — 54% molybdenum
0.019
0.77 Molybdemum For soilless media
Sodium molybdate --38% molybdemum
2.7
77 Molybdemum
Ammonium molybdate — 54% molybdenum
1.9
77 Molybdemum
*Do not apply combinations without first testing on a small number of plants. Wash solution off foliage after application.
Conclusion Micronutrient management is complex and difficult. A more complete treatment of this subject would require more space than we have available here. I hope, nevertheless, that my description of the problem piqued your curiosity. At the very least, I hope that you follow this advice: Don’t guess. Test! In the online version of this article you can find the contact information for some laboratories where you can send your samples for tissue analysis. Visit AmericanHort.org/KC for the online version. Consult with your local Extension Agent for a local plant testing laboratory. Consult with your local Extension Agent for a local plant testing laboratory.
0.25 Manganese
Zinc sulfate — 36% zinc Borax — 11% boron
Sodium molybdate --38% molybdemum
Claudio C. Pasian Department of Horticulture and Crop Science The Ohio State University Pasian.1@osu.edu
This article lists lab references, but such reference should not be considered an endorsement or recommendation by the Ohio State University Extension, nor any agency, officer, or employee at the Ohio State University Extension. No judgement is made either for labs not listed in this article.
2016:11 | 11
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