12 articles tagged "Greens and Salad Crops".

Figure 1. Breakdown of young leaf tissues in the heart of a celery plant

Blackheart of celery is a physiological disorder that causes significant crop loss in major celery production areas. It is characterized by the breakdown of young leaf tissues in the heart of the plants (Figure 1). The affected young tissues turn black, which give it the name “blackheart”.  The cause of blackheart of celery is related to calcium deficiency in the fast expanding tissues, similar to the cause of blossom-end rot of tomato and tip-burn of lettuce. The symptom is more severe as plants approach maturity. Fluctuation in soil moistures; excessive soil fertility, especially nitrogen and potassium; and high soil salinity favor the development of blackheart. Varieties may show different tolerance to the physiological disorder. In addition, the problem can be prevented by avoiding wide fluctuation of soil moisture and over-fertilization. Drench application and foliar spray of soluble calcium direct to the heart of the plant may help to prevent the[Read More…]


Figure 2. Multi-leaf lettuces grown in a high tunnel (photo credit: Liz Maynard)

Winter farmers markets are becoming more and more popular. Lettuce is a primary type of vegetables grown for the market. As we are finishing up summer crops, it is a good time to learn and refresh knowledge about lettuce. This article discusses some of the basics of growing lettuce in high tunnels, as well as the lessons we learned from a trial conducted at Southwest Purdue Ag Center in fall 2016. Lettuce Types Lettuce has multiple morphological forms major types include crisphead (iceberg), butterhead (bibb), romaine (cos), Batavian (summer crisp), and multi-leaf lettuce (salanova). The first decision about growing lettuce is whether to harvest full-size heads of lettuce, or to harvest ‘baby-leaf’ lettuce (Figure 1). These harvest methods require very different production practices. Full-size heads are harvested one time as a single head of leaves. Baby-leaf lettuce is first harvested when single leaves reach about 4 to 5 inches, and[Read More…]


Figure 1. Lettuce in high tunnel showing symptoms of lettuce drop caused by the fungus Sclerotinia sclerotiurum. Photo by Erin Bluhm.

Some of the red and green multi-leaf lettuce plants in Figure 1 are wilted and closer inspection reveals death and soft decay at the crown and well as freeze damage (Figure 2). Getting even closer as in Figure 3 we see white fuzzy mold and find hard black sclerotia 1/8 to ¼ inch across and up to ½ inch long at the base of the plants and in the soil. These sclerotia confirm that the plants have succumbed to white mold or lettuce drop caused by the fungus Sclerotinia sclerotiorum. The lettuce was transplanted in September or October 2016 and the photos taken in mid to late January. We continue to see more plants succumbing to the disease. Infection by this fungus begins when sclerotia buried in the soil produce small mushroom-like apothecia and spores from the apothecia land on susceptible plant tissue, germinate, and invade the plant. Sclerotia can[Read More…]


Figure 1. Aphids on kale crop. Photos courtesy Liz Maynard.

Aphids can be one of the most damaging and hard to control pests during the winter months in high tunnels. The first step to managing aphids is to develop a scouting plan. Aphids reproduce clonally and develop quickly leading to very large population build-up in a short period of time. Therefore scouting is recommended at least three times a week. When examining plants be sure to look at the growing point and underside of leaves, where aphids prefer to colonize (Figure 1). Outbreaks commonly begin on the outer rows or the start of the row so these are places to be sure to include when scouting. In the summer months, successful control has been achieved using a soap/mineral oil spray consisting of 1.5% castile soap and 0.25% mineral oil. Cornell University also reports grower success using the biopesticides Mycotrol O and BotaniGard. These are commercially available formulations of the aphid-attacking[Read More…]


Figure 1. Flea beetles on Brassica (photo credit: John Obermeyer)

Many of our vegetable crops are subject to feeding by one or more species of flea beetles (Figure 1). Flea beetles get their name because they have enlarged hind legs that allow them to jump like fleas. Most species are quite small, and with their ability to jump, often seem to just disappear when disturbed. Flea beetles tend to feed on the leaves, chewing small round holes. When populations are high, the feeding holes with overlap, creating larger holes. Flea beetles tend to be early season pests, primarily because smaller plants are more affected by their feeding. Treatment thresholds vary from crop to crop. For example, eggplants, on of the most commonly damaged vegetable crops, should be treated when there is an average of 4 beetles per plant. For tomato, the threshold is when leaves are 30% defoliated. Crucifers have no particular threshold, so treatment should be made when leaves[Read More…]


Do you grow spinach or lettuce in Northwest Indiana? Drs. Lindsay Gielda and Scott Bates in the Dept. of Biological Sciences at Purdue University Northwest would like to collect a few samples from your farm. They are studying how the endosymbiotic fungi that naturally live on spinach and lettuce might inhibit the growth of pathogenic E. coli strains on these plants. They need samples from a variety of farms (large and small) in order to gain a better understanding of the diversity of endosymbiotic fungi that occur in this area. If your farm is within 60 miles of Westville, Indiana and you would be willing to allow them to collect a sample sometime between 05-01-2016 and 07-31-2016, please call or email Dr. Gielda at (773) 655-6217 or lgielda@pnw.edu.


U.S. EPA approved a supplemental label to use Kerb SC® herbicide in leaf lettuce. Kerb® is a selective herbicide for control of certain annual grasses and broadleaf weeds. It can be used in direct seeded or transplanted leaf lettuce. Application can be made before or after planting but must be made prior to weed emergence. It may be applied at the rate of 1.25 to 5.0 pints of product (0.5 to 2 lb active ingredient) per acre broadcast application. Depending on application rates, 25 to 55 days of preharvest intervals are required. Refer to the label for more application information http://www.cdms.net/ldat/ld9R3003.pdf.


The symptoms of lettuce drop include a white mold that covers much of the plant and the dark, irregular sclerotia that are observed here. (photo: Wenjing Guan).

Cool season crops such as lettuce are becoming a more popular crop among Indiana greenhouse/high tunnel growers. One of the most important diseases of lettuce is known as lettuce drop. The symptoms of lettuce drop are often noticed after the thinning stage, early in the crop development. The early symptoms may include browning of leaves. Later on in the crop development, the outer most leaves of the lettuce plant may wilt. As the disease become more severe, inner leaves may become infected. Eventually, the entire plant may collapse. The plant often has white mold on the leaves and dark irregular fruiting bodies may be observed (Figure 1). The dark fruiting bodies are known as sclerotia. Two different organisms may be responsible for lettuce drop. Sclerotina sclerotiorum and S. minor. Lettuce drop caused by S. sclerotiorum requires a chilling period (52 to 59° F) for the sclerotia to turn into mushrooms smaller than a[Read More…]


Lettuce is grown in channels using the Nutrient Film Technique

Travelling through Indiana last summer, I realized that many growers plant their crops in soil inside their high tunnels or greenhouses. Soilless production offers different benefits and challenges. This is the first article in a series focusing on soilless crop production in high tunnels and greenhouses. Today we are discussing Hydroponics. What is Hydroponics?  The word hydroponics technically means ‘working water’, derived from the Latin words “hydro” meaning water and “ponos” meaning labor. Hydroponics is a method to grow plants using a mineral nutrient solution, in water and without soil. Two types of hydroponics are commonly found: a) solution culture, and b) medium culture. Solution culture types include continuous flow solution culture (Nutrient Film Technique) and Aeroponics. Medium culture types include ebb and flow sub-irrigation, run to waste, deep water culture and passive sub-irrigation systems. History.  The first research published on the production of spearmint in water was conducted by[Read More…]


Kale varieties growing in test plot.

​If you grow kale you may be interested in the ‘You Heart Kale’ effort promoted by Indiana’s Farm to School program for this year’s Food Day. The “Kale Toolkit”  provided by the Indiana Dept. of Education encourages schools to buy kale from local farmers, plant kale in the school garden, let students taste-test kale recipes, and serve kale in the school cafeteria to celebrate Food Day. Food Day is October 24, but schools can pick any day in October to have their official celebration. The toolkit also includes kale recipes that might be of interest to direct marketers. Learn more about Farm to School in Indiana at www.doe.in.gov/nutrition/farm-school.


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