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

245 articles by this author

Article List

Broccoli under Heat Stress

October 21, 2019 - From Issue:
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Figure 1. Broccoli grow leaves in the head. A response toward heat stress (Pictures was provided by ANR educator Luis A. Santiago)

Cool nights have finally arrived after the first week of October. Before, we had quite a few days when temperatures were above 90°F. The unusual high temperature has caused problems on early-planted broccoli. Broccoli is a heat-sensitive crop. The critical period for heat sensitivity is when plants shift growing tips from vegetative growth to flower bud initiation. This is about 10 days before the crown is visible. Temperatures above 90°F during the critical period cause injury on the flower buds. As the crown continues to grow, an uneven head becomes noticeable, and these heads are inclined to be affected by pathogens. Another response broccoli often has toward the heat stress is to grow leaves in the head (Figure 1), although it may be less a concern compared to bud damage. Varieties are varied by heat sensitivity, and they may have slightly different responses toward high-temperature. For example, the very popular[Read More…]

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High Tunnel Off-season Management

October 21, 2019 - From Issue:
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Although high tunnels make it possible for Indiana farmers to grow vegetables year-round, many growers may choose to end the production season in the fall. After a busy summer, it is not unusual that off-season management is overlooked. Nevertheless, these good management practices determine the success of the next year. It is an old lessen, but we can never put too much emphasis on the importance of good management practices during the off-season. Terminate plants after final harvest, and remove crop residues out of the tunnel. The worst scenario I have ever seen was a high tunnel full of weeds in late fall, and a few tomato plants still standing in the middle of the weeds. No doubt, the plant materials provide a cozy environment for insect pests to survive the winter. Under the ground, the roots of tomato plants, as well as roots of several weeds continue to feed[Read More…]

Indiana & NCRAC Water Quality Workshop

October 21, 2019 - From Issue:
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Date: October 26, 2019 8:30 am sign-in Location: Elkhart County Fairgrounds 17746 County Rd. 34, Goshen, IN 46528 Home and Family Arts Building This one-day hands-on workshop will offer a view into aquaculture and aquaponics water quality parameters and considerations. The day will consist of information that will benefit new and established producers. More information about the event and registration: indianaaquaculture.com/shop

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Time to Renew

October 21, 2019 - From Issue:
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This is the final issue of the Vegetable Crops Hotline (VCH) for 2019. Subscribers who receive a paper copy in the mail need to renew. A renewal form is included with this issue. We are providing up-to a three years’ subscription of VCH at a reduced price (1 year for $15, 2 years for $25, and 3 years for $30). You can check the date on the right bottom corner of your VCH envelope to find what year your subscription will last through. You can sign-up for Veggie Texts with the same form. Email subscribers will remain on the subscription list for VCH as long as the email address works. Email subscribers will need to send us an email or call us to sign-up for Veggie Texts. An Indiana Vegetable Grower Association (IVGA) membership form is included here too. IVGA membership no longer automatically includes the VCH subscription. You need to indicate[Read More…]

Southwest Indiana Melon and Vegetable Growers Winter Meeting

October 21, 2019 - From Issue:
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Date: November 14, 2019 5:00 pm (EST) Location: Southwest Purdue Ag Center (SWPAC) 4369 N. Purdue Road, Vincennes, IN 47591 This event is a great opportunity to learn about watermelon, cantaloupe and other specialty melon production regardless if you have been growing watermelon all your life or are new to this crop.  The meeting will start at 5:00 pm with a casual discussion about this production season. We will solicit topics for the upcoming Southwest Indiana Melon and Vegetable Growers Annual Meeting, which will be held in French Lick, IN on March 13, 2020. At 6:00 pm, dinner will be served. Following the meal, we will present the variety trial results including 40 seedless watermelons, 18 personal-size watermelons and 30 varieties of cantaloupe and specialty melons. Any grower interested in becoming a member is invited to attend the meeting. Membership dues are $15 per year and can be paid at this[Read More…]

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Grant Opportunities from NC-SARE

September 12, 2019 - From Issue:

Farmer Rancher Program This program is for farmers/ranchers to explore innovative sustainable agriculture solutions to production, marketing, labor, and other problems. This grant is offered as individual ($9,000 maximum), team of two farmers or ranchers ($18,000 maximum), or group ($27,000 maximum). Projects may last up to 24 months. Proposals are due December 5, 2019. Interested applicants can find the call for proposals online as well as useful information for completing a proposal at https://www.northcentralsare.org/Grants/Our-Grant-Programs/Farmer-Rancher-Grant-Program  Partnership Program This program is intended to foster cooperation between agriculture professionals and small groups of farmers and ranchers to catalyze on-farm research, demonstration, and education activities related to sustainable agriculture.  Partnership Grants are funded for up to 24 months. Up to $40,000 total funding request per application is allowed. The deadline for Partnership Program proposals is October 24, 2019. Interested applicants can find the call for proposals online at https://www.northcentralsare.org/Grants/Our-Grant-Programs/Partnership-Grant-Program

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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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