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
(812) 886-0198 guan40@purdue.edu
Wenjing Guan's website

199 articles by this author

Article List

Upcoming Events

August 1, 2019 - From Issue:
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Vegetable Field Day at Pinny Purdue Ag Center  Date: Aug. 13, 5:00 pm CDT. Location: Pinney Purdue Ag Center. 11402 S. County Line Rd., Wanatah, IN 46390. Just north of US 30 between LaPorte and Porter Counties The public and those who raise vegetables commercially or as a hobby are invited to a vegetable and high tunnel field day on Tuesday, August 13, at Pinney Purdue Ag Center (PAC), 11402 South County Line Road, Wanatah. This Purdue Extension program begins at 5:00 pm CDT. Participants will hear some presentations from Purdue specialists then can choose a track on vegetable production or utilizing fresh vegetables. Laura Ingwell, Purdue Extension entomologist, will provide tips on organic insect management and will discuss the melon pollinator research project she is overseeing at Pinney PAC. Liz Maynard, Purdue Extension commercial vegetable specialist, will review and demonstrate the benefits of biodegradable plastic mulch for use with[Read More…]

Variety Selection is Important for Managing Cucumber Powdery Mildew in High Tunnels

July 22, 2019 - From Issue:
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Figure 1. Powdery mildew on cucumbers grown in a high tunnel.

Powdery mildew is particularly severe in high tunnel and greenhouse growing conditions (Figure 1). It affects a wide range of crops including tomatoes and cucumbers. In addition to using synthetic fungicides to control this disease in high tunnels, we found powdery mildew on cucumbers can also be effectively controlled through variety selection and intensive plant pruning. Cucumber cultivars grown in high tunnels are parthenocarpic. Most of these cultivars are marketed as powdery mildew resistance. However, there are actually a wide range of different levels of resistance existed among parthenocarpic cultivars. In our trials, we found Japanese type cucumbers, especially cultivar Tasty Jade, was very susceptible to powdery mildew; Taurus was less susceptible than Tasty Jade, but much more susceptible compared to most Beit alpha (or mini) type, long English (or Dutch greenhouse) type and American slicer cucumbers. Comparing three long English cultivars in our evaluation, Kalunga was more susceptible compared[Read More…]

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Upcoming Events

July 22, 2019 - From Issue:
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Small Farm Education Field Day at Purdue Student Farm  Date: August 1, 2019 Location: Purdue Student Farm, West Lafayette, IN 47907 The Purdue Student Farm is proud to announce its second annual Small Farm Education Field Day. The event is packed with educational sessions during the morning, followed by a tour and hands-on experiences on the farm. Topics of discussion throughout the day include basic planning tools for a sustainable small farm operation, testing and restoring soils in urban and peri-urban systems, scheduling crops in high tunnels, using different cover crops to build your soil, calculating profits and return on investment using enterprise budgets and food safety plants for small growers and gardeners. During the afternoon there will be a rototiller versus power harrow, high tunnel tomato and sweet pepper production, leaf mold composting, vegetable wash station design, and solar dryer demonstrations. Registration fee is $20. Register here https://purdue.ca1.qualtrics.com/jfe/form/SV_3qQfl05iryF3COp Registration[Read More…]

Results of Wet Condition on Watermelon and Cantaloupe

July 5, 2019 - From Issue:
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The 2019 production season started with above-normal rains. The wet conditions affected agriculture production, including watermelon and cantaloupe. In this article, we will review some of the watermelon and cantaloupe problems that are often associated with wet conditions. Manganese toxicity– This nutrient disorder occurs more often on cantaloupe that is grown in soils with pH lower than 5.5. Although liming before planting is a common practice, it is not unusual that we see soil pH that has dropped below 5.5 in sandy soil, especially during wet years. Manganese exists in soil solution as either reduced (Mn2+) or oxidized (Mn3+) form. Plants take up manganese in the reduced form (Mn2+). The proportion of exchangeable Mn2+ increases dramatically as soil pH decreases, and this reaction is promoted in waterlogged soils with low oxygen condition. As raindrops fall through the air, they dissolve CO2 and form enough carbonic acid to lower the pH of[Read More…]

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Upcoming Events

July 5, 2019 - From Issue:
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Meigs High Tunnel Field Day Date: July 18, 2019 Location: Purdue Meigs Farm, 9101 S 100E, Lafayette, IN 47909 Topics of the field day include Production of specialty melons in high tunnels; Early detection of bacterial wilt; Impact of crop rotation and rootstock on the resilience of high tunnel tomatoes. Lunch and refreshments are provided. Registration is free, but required. Register here https://purdue.ca1.qualtrics.com/jfe/form/SV_0HXQwDluRiOnwAB For questions please contact Lori Jolly-Brown at ljollybr@purdue.edu or (765) 494-1296   Small Farm Education Field Day at Purdue Student Farm  Date: August 1, 2019 Location: Purdue Student Farm, West Lafayette, IN 47907 The Purdue Student Farm is proud to announce its second annual Small Farm Education Field Day. The event is packed with educational sessions during the morning, followed by a tour and hands-on experiences on the farm. Topics of discussion throughout the day include basic planning tools for a sustainable small farm operation, testing and[Read More…]

Strawberry Insect Pest Update

June 20, 2019 - From Issue:
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Figure 2. Yellow striped army worm feed on strawberry fruit.

At the Southwest Purdue Ag Center, we are studying annual strawberry production on plastic mulch. Our hope is to gather information for best production practices in our area. As we learn about insect and disease problems, we will pass this information on to producers. This article is about the insect pests we have observed in our strawberries that were planted in March 2019. Armyworm– Toward the end of the spring harvest, we observed significant damage on strawberry fruit caused by armyworms. Beet armyworm and yellowstriped armyworm larvae were found in the field (Figure 1 and 2).  They feed on both green and ripe strawberries. More than 30% fruit became unmarketable because of the insect feeding. Damage was also observed on flowers. Armyworms also cause significant damage when they chew on strawberry crowns and leaves of summer-planted young strawberry plants. Midwest Fruit Pest Management Guide provides several options for controlling the[Read More…]

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Upcoming Events

June 20, 2019 - From Issue:
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Indiana Horticultural Society Summer Meeting  Date: June 25, 2019. 9:30 am Location: Huber Orchard and Winery, 19816 Huber Road, Starlight, IN 47106 The summer meeting is co-sponsored by Indiana Horticultural Society and Indiana Vegetable Growers’ Association. The meeting will focus on commercial production of fruits and vegetables and farm marketing. All those interested are welcome to attend. A registration fee of $5.00 per family or farm is payable at registration. A catered lunch will be served onsite. This will most likely be fried chicken with vegetables and drinks. There is a $10/person charge for lunch, collected onsite. Please go to the following website to RSVP  https://purdue.ca1.qualtrics.com/jfe/form/SV_6oqUlioijOUNb0x 9:30 am – Convene and registration at Huber Orchard and Winery. 10:00 am – Introductions, a brief walking tour of facilities – winery, market, icecream store, banquet hall 10:30 am – Field tour – apples 11:45 pm – Lunch – $10 – RSVP requested[Read More…]

Upcoming Events

June 6, 2019 - From Issue:
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Indiana Horticultural Society Summer Meeting  Date: June 25, 2019. 9:30 am. Location: Huber Orchard and Winery, 19816 Huber Road, Starlight, IN 47106 The summer meeting is co-sponsored by Indiana Horticultural Society and Indiana Vegetable Growers’ Association. The meeting will focus on commercial production of fruits and vegetables and farm marketing. All those interested are welcome to attend. A registration fee of $5.00 per family or farm is payable at registration. A catered lunch will be served onsite. This will most likely be fried chicken with vegetables and drinks. There is a $10/person charge for lunch, collected onsite. Please go to the following website to RSVP  https://purdue.ca1.qualtrics.com/jfe/form/SV_6oqUlioijOUNb0x 9:30 am    Convene and registration at Huber Orchard and Winery. 10:00 am  Introductions, a brief walking tour of facilities – winery, market, icecream store, banquet hall 10:30 am  Field tour – apples 11:45 pm Lunch – $10 – RSVP requested (see below) 1:00 pm   [Read More…]

Watch for Two-spotted Spider Mites on High Tunnel Cucumbers

June 6, 2019 - From Issue:
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Figure 3. Cucumber cultivar Taurus were grown in the front, cultivar Corinto was grown in the back.

Supported by NC SARE (LNC17-390), we are continuing research for improving high tunnel cucumber production. One of the biggest challenges for growing cucumbers in high tunnels in the summer is two-spotted spider mites. Dry and hot environments featured in high tunnels allow two-spotted spider mite populations to increase rapidly. The mites cause leaf yellowing, necrosis, and defoliation that interfere with plant photosynthesis. Yield can be significantly reduced. The pest also causes direct damage on cucumber fruit, resulting in a sandpaper-like texture to the rind (Figure 1). Early detection is the key for controlling two-spotted spider mites. As soon as two-spotted spider mites are detected, control efforts need to be taken. In the early stage, yellowish specks on the upper side of the leaves may be noticed (Figure 2). Turn the leaf over, on the other side of where the yellow specks are, you may find the presence of two-spotted spider[Read More…]

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Upcoming Events

May 22, 2019 - From Issue:
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Southwest Purdue Agricultural Center Field Day Date: June 27, 2019. Registration begins at 8:30 am. Location: Southwest Purdue Agricultural Center, 4669 N. Purdue Road in Vincennes, IN 47591 Topics related to vegetable production include: Organic Tomato Production: Dan Egel will discuss the Tomato Organic Management and Improvement Project — including foliar disease management of tomatoes. High Tunnel Grafted Cucumber & Specialty Melon Production: Wenjing Guan and Petrus Langenhoven will discuss cucumber and melon production in high tunnels. Applying IPM Principles across Cropping Systems to Increase Insect Pollination and Profitability: Laura Ingwell will discuss best management practices for watermelon production by quantifying pest pressures, pollinator health, and crop yields. Annual Strawberry Production: Wenjing Guan will discuss annual plastic culture for strawberry production in southern Indiana. Other topics include: Termites to the Rescue: In this presentation, Rick Meilan will discuss the use of enzymes derived from termites to control invasive woody species. Removing[Read More…]