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

200 articles by this author

Article List
Figure 1. Cucumbers start to wilt following a night average soil temperature was 58 °F

Chilling injury occurs when temperatures are above 32°F and below 55°F. The plant tissue becomes weakened that leads to cellular dysfunction. The most noticeable visual symptom of chilling injury is leaf and hypocotyl wilt (Figure 1). This is caused by the rapid decline in the ability of roots to absorb and transport water. It also caused by the plant’s reduced ability to close stomata. If temperatures do not improve, plants may be killed. Low temperatures also have an effect on mineral nutrient uptake of the plants. Absorption of ions by roots is difficult, as well as their movement in the above-ground parts of the plants. As a result, chilling injured plants often show symptoms similar to nutritional deficiency. Although warm-season vegetables are all susceptible to frost/freezing damage, their susceptibility to chilling injury varies among plant species. Pepper plants seem to have greater difficulty recovering after chilling injury compared to tomato[Read More…]


Bacterial wilt is a serious pest of cucumbers and melons. This disease is caused by the bacterium, Erwinia tracheiphila. However, it is spread by the striped or spotted cucumber beetle. Most management schemes have concentrated on controlling the cucumber beetle in order to lessen the severity of bacterial wilt. Currently, management of bacterial wilt often takes the form of a soil applied systemic insecticide such as Admire Pro® at transplanting and follow up pyrethroid products applied foliarly about 3 weeks post transplanting. The pyrethroid applications are made when the 1 beetle per plant threshold is met. Every year, there is a melon variety trial at the Southwest Purdue Agriculture Center in Vincennes, IN. In 2018, the trial included several specialty melon varieties. We noticed more bacterial wilt than usual (Figure 1). Therefore, we decided to rate the varieties to see if there were any differences in susceptibility. Figure 2 shows[Read More…]


thumbnail image

Cover Crop Workshop & Field Tour Date: Thursday, April 4, 2019 9:00 am – Noon Location: SEPAC – 4425 E. 350 N., Butlerville, IN 47223  


Figure 2. Personal size (mini) watermelon cultivars.

Watermelon variety trials are conducted every year at the Southwest Purdue Agricultural Center in Vincennes, IN. In the 2018 trials, it included 38 standard-size seedless watermelon cultivars and 10 personal-size watermelons. This article discussed the top yielding varieties in our trials in 2018. The full report of the variety trials, and  information about the previous trials  can be found at https://ag.purdue.edu/arge/swpap/Pages/SWPAPPDFPresentstions.aspx Standard size seedless watermelons Tailgate is a new cultivar from Seminis. First time entered into our evaluation in 2018. Tailgate had the top yield variety in the 2018 trial. It produced large-sized fruit, average fruit weight was 18.5 lb, 37% fruit in 36 counts and 20% in 30 counts category. Firm flesh, good quality. Tailgate was one of the five cultivars that did not have hollow heart fruit among the 12 fruit selected for the quality test. Bottle Rocket had a consistent high yield in both 2017 and 2018 trials.[Read More…]


Figure 1. An orange-flesh watermelon with the tiger-striped rind pattern

With the growing interest from consumers looking for new, unique products, yellow– and orange-flesh watermelons might create opportunities for small-sized growers to differentiate their products. This article answers a few questions you may have about growing and marketing these unique type of watermelons. Yellow and orange-flesh watermelons usually have narrow strips with varying degree of green color as the background. The rind pattern is sometimes called tiger-striped rind pattern. There are also some cultivars that have similar outside appearance as the typical red-flesh watermelons. Like red-flesh watermelons, both seeded and seedless types of yellow- and orange-flesh watermelons are commercially available. Some examples of cultivars are listed in the table below. Table 1. Example yellow- and orange- flesh seedless and seeded watermelon cultivars and their seed sources. Cultivar Flesh color Size (lb.) Shape Seed Source Seedless cultivar Amarillo Yellow 13-15 Round Jo, Si, Ru Lemon ice Yellow 10-12 Oval-round NE, Ho Orange[Read More…]


Tomato and Cucumber growers who are interested in grafting tomato and cucumber plants by themselves may find this information helpful. Step-By-Step instruction of how to graft tomato plants is available from Purdue Extension publication Vegetable Grafting: Techniques for Tomato Grafting https://mdc.itap.purdue.edu/item.asp?Item_Number=HO-260-W as well as a Purdue Extension video https://www.youtube.com/watch?v=7Ufx66Isf88 A cucumber grafting instruction was also recently released. It provides step-by-step guidance of cucumber splice grafting technique. The publication is available at https://www.extension.purdue.edu/extmedia/HO/HO-328-W.PDF


The Indiana Department of Workforce Development is undertaking a major redesign of its Uplink Employer Self-Service system (ESS) to better meet the needs of employers. ESS provides employers with online access to Unemployment Insurance account information, including report submission, tax payments and information on account issues. The first phase of the redesign will be completed by April 30 and will include: online, printable copies of notices and mailings; intuitive menus featuring easier to read fonts and graphics; simplified user roles; consolidated wage and contribution reporting; and fully integrated electronic payment options. “The redesign of the ESS is a much needed and welcome upgrade to the ESS user experience,” said Gina Ashley, DWD Chief Unemployment Insurance and Workforce Solutions Officer. “These upgrades are the result of two years of conducting employer surveys and identifying of best practices. Businesses that use the ESS to access their Unemployment Insurance account, submit reports and[Read More…]


Cover crops can be a useful conservation practice for improving soil health, scavenging and recycling nutrients, reducing erosion, and contributing to more resilient cropping systems over the long term.  Two new extension publications about Cover Crop Recipes for Indiana are available at the Purdue Education Store: https://edustore.purdue.edu/item.asp?Item_Number=AY-356-W https://edustore.purdue.edu/item.asp?Item_Number=AY-357-W There is also a webinar scheduled on Feb. 22 at 10 am EST for a discussion of the new Indiana cover crop recipe. More information about this event and the publications are available at the Midwest Cover Crops Council website http://mccc.msu.edu/getting-started/cover-crop-recipes/


thumbnail image

Please welcome Dr. Brock Harpur as a new Assistant Professor in Pollinator Biology. He joins the Department of Entomology, Purdue University.  A native of British Columbia, Canada, Brock is a specialist in honey bee genetics and the evolution of social insects. He will take up honeybee research program plus provide extension expertise to bee-keepers both professional and amateur, and citizens concerned about bees and pollinator conservation. Please contact Dr. Harpur at bharpur@purdue.edu  


Welcome to a new year of the Vegetable Crops Hotline (VCH), Purdue Extension’s newsletter for people in the business of growing vegetables. As usual, we will have fifteen issues throughout the 2019 growing season. The first issue of the year is sent to all who subscribed to VCH via US-mail in 2018 as well as new subscribers for 2019. To continue receiving future copies through US-mail, renew your Hotline subscription using the form attached to this issue. Note that we provide an up-to three years’ subscription of VCH with a reduced price. If you receive the issue through email, you will continue to receive the newsletters on the issue dates. In addition, you will receive emails if there are articles or announcements that need your immediate attention. These articles will be posted under Hot Topics and be included in the next issue. All the previous articles published in VCH are available on the website. Frequently we include links to websites or publications available on-line. If you aren’t[Read More…]