Wenjing Guan

Vegetable Crops Hotline Editor & Clinical Engagement Assistant Professor
Department of Horticulture and Landscape Architecture
Area(s) of Interest: Commercial Vegetable and Melon Production
Wenjing Guan's website

142 articles by this author

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Following the success of last year’s Summer Field Tour at Tuttle Orchards, this year we are again planning a combined summer field tour with the Indiana Horticultural Society, the Indiana Vegetable Growers’ Association and the Indiana Farm Market Association. We will be hosted by Garwood Orchards in La Porte, IN. While we encourage membership in these industry organizations, all those who are interested are welcome and invited to attend, regardless of membership status. Garwood Orchards is one of the largest and best managed orchards in the state. It may seem puzzling that they can manage such a large operation and manage it so well. That’s why we’re visiting – to not only be inspired but learn a few of their tricks and see how they do it. They have aggressively planted new cultivars and crops and have been on the forefront of adopting new technologies. They are major producers of[Read More…]


Figure 1. Blossom end rot of tomato.

We recently received several calls reporting blossom end rot of tomatoes (Figure 1). Although blossom end rot is caused by deficient supply of calcium to the developing fruit. The occurrence of this physiological disorder often relates to inconsistent supply of water. As a general rule, vegetables require 1-1.5 acre-inches of water per week. Since there is no rain in high tunnels, all the required water should be applied through irrigation. How does one determine if enough water has been applied to vegetables? This article provides some ideas. The first information needed is the irrigated area. For example, tomatoes are growing in a 30 × 96 high tunnel with 6 beds that are about 4 feet wide. Then the irrigated area is about 2,304 square feet (6 × 4 × 96 = 2,304). An acre has 43,560 square feet. So the irrigated area is roughly 2,304 / 43,560 = 0.05 acre.[Read More…]




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Southwest Purdue Ag Center High Tunnel Tour Date: June 13, 2018 7:00-9:00 pm Eastern Time Location: Southwest Purdue Agricultural Center, 4369 North Purdue Road, Vincennes, IN, 47591 The SWPAC high tunnel tour will be held on the evening of June 13, 2018. Seedless cucumber production in high tunnels will be the highlight of this year’s event. You will see 16 cucumber varieties grown in a high tunnel, and be able to taste them. We will share with you yield results of grafted cucumber plants that have started to produce since middle April in an unheated high tunnel. You will also see cucumbers grown in the high tunnels with different pruning and trellising systems. Entomologist Laura Ingwell will join us at the event to discuss cucumber beetle management approaches. Other things you will see at this event include: summer squashes growing in a high tunnel; different pruning and trellising systems for growing tomato and pepper;[Read More…]


Would you like to learn more about biological control and how to use it successfully? New York State Integrated Pest Management biocontrol specialist Amara Dunn has a new blog – “Biocontrol Bytes” (https://blogs.cornell.edu/biocontrolbytes/). Short articles are posted approximately once a month to share information, answer stakeholder questions, and connect readers to other relevant resources. Subscribe using the green button on the right side of the page in order to receive email updates when new articles are posted.


Three videos on in-row weeding tools (Finger weeder, Torsion weeder, Tine harrow) were developed at the Michigan State University Department of Horticulture. Each video is 20 minutes: introduces the tool, how it works, different models, show adjusting the tool in the field, and a short interview with a farmer who uses the tool. These videos can be accessed at the MSU Mechanical Weed Control Channel https://www.youtube.com/channel/UCH-k889oYbUaEznvgiDtrOQ


Figure 1. A cucumber plant grown in a high tunnel died because of bacterial wilt.

Bacterial wilt is one of the most destructive diseases in high tunnel cucumber production. The reason bacterial wilt is so important is because, like other wilt diseases, it ties up with the entire vascular system of a plant, causing systemic effects (Figure 1). The relatively less important roles that other cucumber diseases play also make bacterial wilt the major limitation for high tunnel cucumber production in Indiana. For example, common cucumber diseases such as angular leaf spot, anthracnose and Alternaria leaf blight seldom occur in a high tunnel scenario; improved resistance to powdery mildew was observed in some of the newly developed cucumber varieties; downy mildew in general does not occur in Indiana until end of the high tunnel cucumber production season. The causal organism for bacterial wilt of cucumbers is Erwinia tracheiphila. After the bacteria enter the plant vascular system, it multiplies quickly. As a result, it interferes with[Read More…]


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Southwest Purdue Ag Center High Tunnel Tour Date: June 13, 2018 7:00-9:00 pm Eastern Time Location: Southwest Purdue Agricultural Center, 4369 North Purdue Road, Vincennes, IN, 47591 The SWPAC high tunnel tour will be held on the evening of June 13, 2018. Topics that will be discussed include: Grafting cucumbers for season extension; Seedless cucumber and summer squash variety evaluations in a high tunnel; Different pruning and trellising systems for growing cucumber, tomato and pepper in a high tunnel; Grafting tomatoes for improved yield; Cucumber beetle management; Annual plasticultural strawberry production with an innovative low tunnel system. Registration will begin at 6:30 pm. The tour is free; to register please call (812) 886-0198. For more information please contact Wenjing Guan (guan40@purdue.edu). This event is sponsored by North-Central Sustainable Agriculture Research and Education.   2018 Indiana Hort Society Summer Field Day Date: June 26 Location: Garwood Orchard, LaPorte, IN Please contact[Read More…]


Nematology lab at Purdue University will be closing at the end of June. The first of June is the last day the lab will accept samples. A list of private and public nematology labs can be found here. Please contact these labs for their requirements for nematode sample submission. Click here to view the listing for private and public nematology laboratories.