Saturday, February 22, 2014

New and unique cabbage cultivar

Ajay Nair
Department of Horticulture
Iowa State University

Last fall our lab experimented with a new and unique cabbage cultivar called 'Caraflex'. Results from the study show promise for this cultivar as a potential crop for Iowa and the Midwest. This cabbage has small heads with good wrapper leaves for insect and sun protection. Leaves are tender, crunchy, and have mild cabbage flavor. This cabbage seems to more like a blend of two vegetables- cabbage + lettuce. Average yield were in the range of 3,000-4,000 lbs/A

Friday, October 25, 2013

Sweet potato harvest

Ajay Nair
Department of Horticulture
Iowa State University

Our sweet potato harvest took place on October 17th, 2013, three weeks later than 2012. Overall the crop grew well. Slips were planted on June 7, 2013 on black plastic mulch. The mulch helps increase soil temperature and suppress weeds. Weeding was minimal, only two times, until the canopy closure. The crop was affected by Japanese beetles but the plants came out of it gradually.

The harvest team
It is picking time !

The undercutter; used to lift potatoes
Undercutter in action

We conducted two experiments this year, one identifying suitable cultivars for Iowa growing conditions and the other investigating appropriate spacing of sweet potatoes. Data will be soon analyzed and made available through ISU Research Farm Progress Reports and at

Wednesday, October 2, 2013

Cover crop status

Dr. Ajay Nair
Department of Horticulture
Iowa State University

We seeded our cover crops during on 09-05-2013 for 2014 field study that will focus on the use of cover crops and conservation tillage practices in vegetable production systems. The plot is located at the Horticulture research Station, Ames, IA. So far cover crops are doing great. Pictures below were taken on 09-26-2013.

This was the second seeding of cover crops as the first seeding was not uniform. We decided to tear the plot and seed again. Both times Tye Pasture Pleaser seeder was used. The reason for the non-uniform germination of the first seeding was attributed to seeding depth. Cereal rye is sensitive to seeding depth. Although we had set the seeding depth between 1 to 1-1/4 inch, close examination of showed that the majority of seeds were at 1-3/4 to 2 inch deep. One would assume the rye to germinate and emerge at that seeding depth, but it is debatable. In our experience, the second seeding, in which rye was seeded at 3/4 to 1 inch depth, germination was excellent and the emergence was uniform (see pictures above).

Growers should monitor the seeding depth carefully as it could significantly affect emergence of cover crops. Small seeded cover crops like clovers and mustard should be handled even more carefully. 

Sunday, June 23, 2013

Cover Crop Workshop/Field day

Dr. Ajay Nair
Department of Horticulture
Iowa State University

Ames, Iowa – The sustainable vegetable production lab in collaboration with researchers at Iowa State University, USDA-National Laboratory for Agriculture and Environment and USDA-SARE are teaming up to offer three cover crop workshops this Fall at following locations:

September 27 (Friday) – Armstrong Research Station, Lewis, IA
October 4 (Friday) – Horticulture Research Station, Ames, IA
October 11 (Friday) – Muscatine Island Research Station, Fruitland, IA

Funding for these workshops is provided by USDA-SARE Professional Development Grant Program. Workshops are geared towards commercial horticulture field extension specialists, county extension horticulturists, regional food systems working group members, local food organizations, IFVGA & PFI board members, and IDALS & NRCS personnel. Fruit and vegetable growers interested in learning about cover crops are also welcome. This workshop is co-sponsored by The Leopold Center for Sustainable Agriculture.

Participants attending the workshop will learn about cover crop types, planting, management, benefits, and issues associated with cover cropping in fruit and vegetable cropping systems.  Depending on weather, there will be an opportunity to assess cover crops under field conditions. Live cover crop plants will also be on display inside.  

Registration is free but required for arranging food. Please contact Dr. Ajay Nair (; 515-294-7080).

The tentative agenda for the workshop is given below:

9:30am – 9:45
Registration and refreshments
9:45am – 10:00
Welcome, Dr. Ajay Nair, Department of Horticulture, ISU
10am - 10:45
Benefits of cover crops in crop production systems
Dr. Tom Kaspar, USDA-NLAE
10:45 - 11:30
  Envisioning a cropping systems approach
  Dr. Andy Lenssen, Agronomy, ISU
11:30 - 1:30
Lunch and field visit
1:30 - 2:15
Integrating cover crops in fruit production systems – Dr. Gail Nonnecke, ISU
2:15 - 3:00
Cover crop options for vegetable growers – Dr. Ajay Nair, ISU
3:00- 3:15 pm
Discussion, Evaluation, Adjourn

Wednesday, June 19, 2013

Potato Blackleg

Ajay Nair
Department of Horticulture
Iowa State University

Recently a number of growers had called in and also sent samples of their potato plants. The main symptom mentioned was the development of a mushy, black, soft lesion on the stem at the ground level (see pictures below). These symptoms are caused by bacterium called Erwinia carotovora and can take many forms (blackleg, aerial stem rot, or tuber soft rot). Bacteria either enter the seed potatoes and lower stems through wounds and injuries, or move directly from contaminated seed pieces to lower stems.  
Blackleg infection
Stem collapse

Affected foliage

Abundant moisture at the surface of the wounded tissue is needed for infection and continued high humidity after infection favors spread of the disease in the plant. This year's wet spring weather is conducive for the spread of this disease. The decay of seed pieces in the soil by fungi and other organisms may also provide conditions for blackleg disease to develop.

The blackleg bacterium survives poorly in soil. All evidence suggests that the blackleg bacterium does not survive very well outside of association with host plant tissue. Hence, the seed tuber is the most important source of inoculum in the blackleg disease cycle. Removal of blackleg affected plants including below-ground portions is the best option. Take steps to prevent contact of diseased tissue with other plants in the field. It is unfortunate that there is no effective chemical control to manage this disease. The first and the most effective line of defense is the use pathogen-free tubers for seed. Warming of seed tubers to about 55°F before planting also helps. Seed treatment with fungicides do not directly affect these bacterial pathogens, but fungicides can reduce invasion by other fungi and therefore reduce opportunistic infection by Erwinia spp.

Monday, May 27, 2013

A wet Spring

Ajay Nair
Department of Horticulture
Iowa State University

This past week I time traveled to my nursery days and the song which I wanted to sing badly was "Rain rain go away...Come again another day, Little Johnny wants to play". Things have been fairly wet this spring. The ground is saturated and it is hard to get in the field and plant. We need the rain but it is the timing that is causing  issues. It rains and the ground starts to dry in 3-4 days but then it rains again. As compared to last year we are late in our plantings. Last Tuesday we flail mowed our cover crops (cereal rye) and gave a shallow till to dry the soil faster. We waited for three days and last Friday when we got a small window, we went full throttle and banded fertilizer and laid plastic. Banding fertilizer in the area where the plastic is laid has several advantages:
1. Less fertilizer is used
2. Fertilizer not available to weeds that grow in the alley-way between raised beds
3. Promotes sustainability by reducing fertilizer usage

Above: Cover crops being flail mowed
Below: Plastic mulch layer in action
It is unfortunate that the rain is disrupting and delaying planting, but vegetable growers should take utmost care before deciding to run any machinery in their fields. One of the concerns is soil compaction. Under wet conditions, the effect of soil compaction could go as deep as 2 feet, depending upon the axle load of the tractor.  Heavily compacted soils contain few large pores and have reduced rate of water infiltration and drainage in the compacted layers. This can can increase runoff, thus increasing soil and water losses. Compaction directly limits root growth of crops and has the potential to reduce crop growth and yield. This year it might a little tight to find the perfect soil moisture or field condition to lay plastic mulches, all we can do is be prepared and ready to get in to the field as soon as there is an appropriate rain-less window. Meanwhile, on a lighter note, I will continue with my nursery rhyme.....Rain Rain go away....come again another day......
Normal and compacted soil

Monday, May 20, 2013

Planting time musing

Ajay Nair
Department of Horticulture
Iowa State University

Weather is fascinating. It surprises you in many ways. After months of conversation about not having moisture in the ground and a slow recovery from drought, here we are, talking about too much water in the ground! The level of anxiety among fruit and vegetable producers is on the rise. We at the Horticulture Research Station are on the same page. Every time one waits for a sweet 2-3 window to till the soil and roll the plastic mulch layer, a thunderstorm rolls in with 1-2 inches of water!

Things are a little different at the eastern end of the state, thanks to the well-drained sandy soils. It rains but you can be in the field the next day. But they have their own woes with lower organic matter and water holding capacity soils. At the Muscatine Island Research Station, Fruitland, IA  our sweet corn is 2-3 inches tall and the potatoes have sprouted and getting ready to come up the soil. We installed lysimeters in our potato sweet corn biochar study on 05-08-2013 to collect water leaching out of those soils. It will be an interesting finding to know how much of nitrates are being tied up by the biochar. A large number of high tunnel growers would be happy that this intermittent rainfall is not creating problems with their planting schedules. Most high tunnel growers have planted their crop and are looking forward to a good growing year. Our tomato plastic mulch study at the Armstrong Research Station, Atlantic, IA got planted 05-10-2013.
    Sweet corn at Muscatine
Lysimeter installed
Plastic mulch study at Armstrong Research  Station
Our lab was all excited for today (05-20-2013) to start laying our plastic mulch but the rain last night played a spoilsport. Oh well, there are things to get done in the lab. So here we are, waiting 2-3 days for that perfect level of soil moisture where the plastic mulch is laid down to perfection (straight, tight, and with good soil contact).