Liz Maynard

Clinical Engagement Assistant Professor of Horticulture
Department of Horticulture and Landscape Architecture
Liz Maynard's website

79 articles by this author

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The wet spring has likely delayed some planting of pumpkins. What does delayed planting mean for yield? Data and observations from Purdue Ag Centers offer some perspective to supplement other experience. Figure 1 shows how pumpkin yield was affected by planting date for 6 trials. Each line represents a different trial. The Y-axis shows relative yield within in each trial. Yield of the first planting date for each trial is set to 100. For the two trials at Pinney Purdue (orange lines, PP2002 and PP2003), pumpkins seeded June 20-25 yielded 70%-85% of pumpkins seeded by early June. In the 1995-1996 trials at Southwest Purdue Ag Center (light green lines, SW1995 and SW1996), pumpkins transplanted June 25-30 produced about 50% of those transplanted two weeks earlier (June 10-15). Transplanting two weeks later (July 10-15) produced only 30% of the yield compared to the June 10-15 plantings. In the 1997-1998 trials at[Read More…]


Figure 2. Wilt of watermelon seedlings due to grown in a high EC medium.

Producing healthy transplants is a critical step for a successful growing season. Choosing the proper growing media is an important first step. Supported by a USDA Specialty Crops Block Grant through the Indiana State Department of Agriculture, researchers from Purdue have been evaluating different organic growing media with and without adding supplemental organic fertilizers for tomato and cucurbit transplant production. In this article, we have highlighted a few transplant symptoms that are associated with growing media with excessively high or low electrical conductivity (EC) or pH. It is always a good idea to test EC, pH, and other important nutrient content of a medium when you are making your own or using an unfamiliar media. Most soil laboratories provide a saturated media extract test that provides information on these important parameters. More information about this test and suggested range of EC and pH can be found in this article http://www.soiltest.uconn.edu/factsheets/InterpSMEGreenMedia.pdf[Read More…]


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Dual Magnum® has had a special local needs (24C) label in Indiana for use on transplanted bell peppers and other vegetables for a number of years. Last week the label was amended to include additional small fruit and vegetable crops, including asparagus. The new 24C label is available on the National Pesticide Information Retrieval System web site: http://npirspublic.ceris.purdue.edu/state/state_menu.aspx?state=IN. To find it, type “SLN IN” and “130003” in the first two boxes for “EPA Registration Number” and click the search button. The product report will show  “DUAL MAGNUM – TRANSPLANTED BELL PEPPERS.” Click on the ALLSTAR symbol. On the page that opens, click on the Company Label ID number “IN0816048DA0319.” This will open a pdf of the label. If you decide to use the product, carefully read and follow the label instructions.


Bolting of crops overwintered in high tunnels is common in the spring. ‘Bolting’ refers to lengthening and blooming of the flowering stalk. Bolting is often a problem because the quality of the marketable part of the plant declines. Also, plants subject to bolting are programmed to die once they complete flowering and seed production so yield will decline in quantity as well as quality. Sometimes bolting is not a problem because the stalk, buds, and flowers can be sold as a new product while they last; this is often the case with kale,  mustards and related crops. Crops susceptible to bolting include those in the mustard family such as kale, mustards, tatsoi, bok choy (pac choi), mizuna, turnip, radish, etc.; carrots; beets and in some cases Swiss chard; onions; lettuce; and spinach. (Figure 1)   Bolting is triggered by environmental conditions. Some plant types are triggered to develop flowers by[Read More…]



Presentations from many past Purdue educational programs for vegetable growers are available online at https://ag.purdue.edu/hla/fruitveg/Pages/presentations.aspx. Slides from the 2019 Illiana Vegetable Growers Symposium are available now. Indiana Hort Congress presentations will be available soon. 


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Getting seedlings off to a good start begins with a good growing medium for transplants. Growing media for organic production must meet the guidelines set out by the National Organic Standards Board, including not containing any synthetic substances (unless they have been approved for that use) or any prohibited materials. A number of products meet those criteria, and many of them are listed by the Organic Materials Review Institute (OMRI) to document that they meet the criteria. Last year, with funding from a USDA Specialty Crops Block Grant through the Indiana State Department of Agriculture, a group at Purdue began evaluating commercially-available, OMRI-listed growing media for vegetable transplant production (Table 1). Table 1. Growing media used in transplant production trials, 2018. Product Abbreviation Source Johnny’s 512 J512 Johnny’s Selected Seeds Morgan Composting 201 M201 Morgan Composting Penn Valley Potting Soil PENN Penn Valley Farms PromixMP Organik PMPO BFG Supply Seed[Read More…]


Vegetable growers will find information-packed sessions at the Indiana Hort Congress next February. A few of the featured topics are highlighted in this article. Visit inhortcongress.org to see the full schedule and register. Climate will be the focus on Tuesday afternoon in a session sponsored by the USDA Midwest Climate Hub, Midwestern Regional Climate Center, and Purdue Extension. Climatologists and production specialists will take a look at existing climate and weather tools useful for Indiana vegetable and fruit growers. They will also generate discussion on what kinds of information about climate and weather would make planning and production easier in future. They will take results of that discussion back to the ‘shop’ to help plan future work. This will be an excellent opportunity to get up-to-date information about climate AND to help shape what kind of climate information is available and how you can get it in the future. Bring[Read More…]


On April 17, 2018, Purdue University and Indiana University Bloomington teamed up to present a webinar about using high tunnels in Indiana. The recording is now available on the Purdue Extension Youtube channel at https://youtu.be/dpm4t4Ws5nQ. The 95-minute webinar introduces the upcoming High Tunnel Handbook for Indiana growers and summarizes key findings and recommendations from a recent study about high tunnel use in Indiana. Key points about winter production from a SARE partnership project wrap up the session.


Figure 1. Top left: old plastic viewed from inside High Tunnel 1. Top right: old plastic as it is being removed. Bottom left: old plastic on left and new plastic on right over a piece of lined paper. Bottom right: High Tunnel 1 with new plastic covering.

Have you ever wondered how much difference new plastic would make in terms of light getting to crops in a high tunnel? We replaced 6-year-old plastic on High Tunnel 1 at Pinney Purdue Ag Center last week. Figure 1 below shows the high tunnel before and after recovering, and pieces of the old and new plastic. We had a sensor measuring PAR (photosynthetically active radiation, light available for plant use in photosynthesis) in the structure, and a similar sensor in High Tunnel 2, which had new plastic in Dec., 2017. The Ag Center also has an automated weather station that measures solar radiation. Here is what these sensors showed us (Figure 1). Figure 2 shows the PAR readings throughout the day in the two high tunnels and solar radiation outside. High Tunnel 1 had the 6-year-old plastic. The plastic was removed on July 9. On July 7 and 8, before[Read More…]