Monday, December 5, 2011

Great Plains Growers Conference January 5th - 7th 2012

I am sure a number of you are aware of the Great Plains Growers Conference in Missouri. Fruit and vegetable growers from across Missouri and the Midwest should make plans to attend the Great Plains Growers Conference and Trade Show on January 5th, 6th and 7th, 2012, at the Fulkerson Center on the Missouri Western State University campus, St. Joseph, Missouri.

The conference will cover many topics including:  fruit and vegetable production, beginning and advanced organic, high tunnel operation, community supported agriculture, agritourism, beekeeping, food safety, farmers market, urban/community gardening, marketing and cut flowers.  The conference also features a trade show with dealers in equipment, tools, seed, chemicals, containers and other horticulture supplies. With all the conference has to offer it is one of the most comprehensive vegetable conferences in the Midwest. A program and registration form is on the web:   or call the Buchanan County Extension office (816) 279-1691.  Pre-registration is open until December 23rd 2011

Sunday, October 9, 2011

How about harvesting lettuce for thanksgiving !

Ajay Nair
Department of Horticulture, Iowa State University

Fresh, crisp, and savory butterhead lettuce for thanksgiving ! at least that is what our lab is aiming for. We recently planted a lettuce trial at the Iowa State University Horticulture Research Station to evaluate the feasibility of a lettuce crop planted as late as 3rd October. Lettuce transplants were grown in the greenhouse for 3 weeks and later hardened off outside for a week. The objective of the study is to evaluate  season extension strategies through the use of row covers and high tunnels. Lettuce transplants were planted outside and in high tunnel on 3rd October 2011.  We planted two rows of lettuce on raised beds with plastic; 10 inch spacing between rows and 8 inch spacing between plants within a row.  Row cover will be installed during the second week of October. 

Transplanting in high tunnel
Field planting of lettuce

Lettuce is an excellent cool season crop that can be grown in 70 days from seed to harvest. Transplant production takes around 20-25 days (including hardening period) followed by 40 to 45 day growth leading to harvest. Lettuce is adapted to cool growing conditions with the optimum temperatures for growth of 60 to 650F. Sensors have been installed both above and below ground to record soil and air temperature. Results from the experiment will provide data on microclimate modification resulting from the use of row covers. Hopefully our results will provide growers with useful information on season extension strategies and a green thanksgiving meal ! 

Monday, September 12, 2011

Winter rye: a versatile cover crop

Ajay Nair
Department of Horticulture, Iowa State University

Winter rye (Secale cereale L.) is one of the most popular and versatile cover crop in many regions of United States. Because of its cold hardiness winter rye is the only cover crop that can be planted as late as in November or even December in the Midwest and the Northeast. Rye has a wide seeding range from 60-120lb/A and is relatively less expensive ($12-15 for a 50 lb bag). Winter rye can also be grown in mixtures with a legume such as hairy vetch. When growing a winter rye and legume mixture, the rate of winter rye seeding should be reduced to half of its original seeding rate.

Rye cover crop in spring
Cover crop being mowed

Once established in the late fall, rye roots hold the soil protecting it from erosion and compaction due to rains in the fall and spring. The above ground biomass helps captures residual nitrogen that would have otherwise leached away. Rapid growth of rye plant shades the ground and suppresses growth of winter weeds.   Winter rye and its residues release plant growth-inhibiting substances called alleclochemicals that are active against suppressing weeds such as pigweeds, lambsquarters, purslane, and crabgrass. A fast-growing rye cover crop competes strongly for light, nutrients, moisture, and space, and can thereby suppress weed growth and development. As the temperatures increase in the spring, rye produces large biomass which is generally mowed and incorporated into the soil. This stimulates soil microorganisms and adds soil organic matter. Also, because of its potential to produce large biomass, rye has been successfully used in no-till cropping systems, especially for vegetables such as pumpkins and squashes.  
All of these characteristics make winter rye an excellent cover crop for our region and depending upon their rotation plans growers should consider incorporating rye into their production systems. To summarize, benefits of rye cover crop include:
1) Reduction in soil erosion
2) Weed suppression
3) Improvements in soil physical, chemical, and biological properties
4) Recycling of nitrogen and other nutrients
5) Enhancement of cropping system diversity
6) Habitat for beneficial insects
7) Use in no-till production systems

Thursday, September 1, 2011

Its time to cover our soil !

Ajay Nair
Department of Horticulture, Iowa State University

When it comes to reducing soil erosion, suppressing weeds, improving soil fertility and health, increasing water holding capacity, and soil organic matter, there is nothing that comes to mind other than COVER CROPS. Cover crops are crops that are grown to cover bare soil between cash crop plantings, however its impact on biological, chemical, and physical parameters of a production system is far reaching and substantial. Cover cropping provides numerous benefits (mentioned above) which make them attractive and useful in any cropping system.  As we are inching towards our fall season, some overwintering cover crops that could be fall planted in Iowa include winter rye, hairy vetch, oats, winter wheat, and some clovers. Although there are a number of choices, growers should chose cover crops that would fit their cropping system and addresses a specific need or problem. If addition of organic matter and weed suppression is a priority, then winter rye would be a better choice. Leguminous cover crop for example  hairy vetch could be utilized when addition nitrogen is the primary goal.

Our lab in the Department of Horticulture at Iowa State University recently set up a cover crop study focusing on cover crop combinations that would enhance nutrient cycling, soil biology & quality,  and improve vegetable production.We are testing winter rye and some other cover crops, individually and in combinations, to develop cover cropping systems that can be utilized for vegetable production in Iowa.  Some aspects of interest include weed suppression, nitrogen management, and crop production. Cover crops seeds were recently broadcasted, incorporated and irrigated (pictures above).

Sunday, August 21, 2011

Heart-shaped leaf that doesn't want to leave !

Ajay Nair
Department of Horticulture, Iowa State University

Heart-shaped objects not always bring fun and joy to our lives, certainly not this one. This weed, Abutilon Theophrasti, commonly referred to as velvetleaf, buttonweed, wild cotton, or Indian mallow has been slowly invading soils under vegetable production. Flower and seeds are produced from July through October and the seeds can remain viable in the soil for about 20-40 years. The plant is 3-7 feet tall and has  large heart-shaped leaves usually 2 to 5 inches wide. Velvetleaf causes the most concern in row crops, however, it can create problems in vegetable production as well. The plant can compete with vegetable crops for water, nutrients and due to its erect growth habit can also shade plants in its vicinity.

It has been reported that leaves and seeds of this plant carry allelopathic chemicals that inhibit the germination and growth of crops, such as radish and turnip.  A number of pre- and post-emergent herbicides are available to control velvetleaf, but more importantly, steps should be taken to reduce its seed bank in the soil. Crop rotation, avoiding excess N application, and hand pulling small populations (remove from the field or burn, since the seeds will ripen after the plant is pulled) will help to control velvetleaf. Velvetleaf becomes less of a problem in no-till systems because if seed germinates on the soil surface, it dies. Some amount of biological control also occurs (velvetleaf seed beetle destroys developing seed; fallen seeds are eaten up by mice and ground beetles) but the best practice is not to let the plant go to seed and, if it does, then removal and destruction of the plant is the next alternative.

Friday, August 12, 2011

Snap Bean "Blossom Drop"

Ajay Nair
Department of Horticulture, Iowa State University

An interesting plant sample came in yesterday from one of the snap bean growers from Hancock County, Iowa. Apart from the description of a potential disease, which the plant diagnostic lab will figure out soon, the information sheet also contained a note: "The crop flowered profusely but is not bearing any pod". Pictures below show few to almost no pods on the plant.

This unusual event is called "Blossom-Drop" which is quite common in peppers, snap beans, and tomatoes.  There are multiple causes for this to occur such as dry windy conditions, excessive use of nitrogenous fertilizers, but the most common cause is high temperature. Tomatoes, peppers and beans are sensitive to prevailing air temperatures with regard to setting fruit. When the day temperatures are above 90 degrees, it affects pollen viability and thus adversely affects pollination. If the flower isn't pollinated, it dies and falls off.

Another important aspect to consider is irrigation. Green beans are particularly susceptible to blossom drop under water stress. Growers should carefully monitor crop water requirement and irrigate whenever needed (depending upon soil type). For growers confronting 'blossom drop', there will be some yield reduction but when temperatures turn cooler new flowers form which would set new pods.

Tuesday, August 2, 2011

Irrigation: worth an investment

Ajay Nair
Department of Horticulture, Iowa State University

Past 2-3 weeks have been extremely brutal in Iowa in terms of high heat and humidity. Most of our daily conversation revolves around 'heat index', a word we constantly hear on television. Plants, similar to us, have their saga to share. Extreme heat has taken its toll on them as well. Crop water requirements depend on crop type, stage of growth, and evaporative demand. In hot weather conditions plants transpire large amounts of water that needs to be quickly replenished to ensure continued growth and development. Failure to replenish water, can lead to several issues apart from wilting. Last week (25 July 2011) I was in the Western part of Iowa visiting some fruit and vegetable growers. One of the problems I noticed in tomatoes is in the picture below (click on the picture to expand):

According to Dr. Hank Taber (Professor Emeritus, Iowa State), the above pictures show what is called 'russetting' or 'micro cracks' in tomato fruit. This occurs under extreme hot conditions coupled with  lack of water for plant uptake. Tomato skin becomes patchy, rough, and develops cracks which can cover large areas on the fruit. Such fruits quickly become non-marketable and can lead to significant loss of revenue to the grower. To prevent this from happening growers should provide ample amount of water in a timely and controlled manner. Although, setting up and installing irrigation could be an expensive operation, it is a critical component for successful vegetable production. It is worth an investment which always pays off !

Thursday, July 28, 2011

Tomato Leaf Mold

Ajay Nair
Department of Horticulture, Iowa State University

Tomato leaf mold is a fungal disease caused by Fulvia fulva. It occurs mostly under greenhouse conditions where relative humidity is high. When humidity is high, the fungus develops rapidly on lower leaves and
progresses upward. Significant yield reduction could occur if the fungus is not controlled early. Pictures shown below were taken in a greenhouse located near Cedar Rapids, IA in the second week of July 2011.

Symptom on upper side of leaves appear as small, pale green, or yellowish spots. On the corresponding lower side, the fungus sporulates producing darker colored area. Growers should consider taking following steps to manage tomato leaf mold disease:

1. Provide good ventilation in the greenhouse. Use fans to circulate the air inside
2. Whenever possible, keep relative humidity below 85%
3. While transplanting maintain adequate row and plant spacing to ensure sufficient air movement. Remove suckers to reduce shading and maintain proper plant growth
4. Avoid wetting leaves while watering
5. Reduce primary inoculum by disposing affected plant debris after harvest.
6. Some fungicides to control leaf mold include Dithane, Revus Top, Tanos, and Inspire. Use fungicides as per  label instruction and guidelines

Tuesday, July 26, 2011

Spray but not sway - Roundup damage on tomatoes

Ajay Nair
Department of Horticulture, Iowa State University

We are obsessed with things that are round.....cookies, pizza, pies, and now ROUNDUP !  Weed control had never been easy until the formulation called Glyphosate which is a non-selective, broad-spectrum, systemic herbicide and an active ingredient in Roundup. Care should be taken to minimize spray drift while applying this herbicide. Roundup spray drift can cause serious injury to non-target plants.

Pictures below show roundup damage on tomato plants growing inside high tunnels (compare with the rows behind). The entire row of plants growing on the outer edge of the tunnel was damaged due to roundup drift from adjacent field. Symptoms include distorted new growth with cupped leaflets. Extent of damage on tomato crop depends on factors such as  stage of growth, amount of exposure, cultivar, etc.
Precautions to avoid such damage:
1. Avoid spraying under breezy conditions
2. Utilize a shield to prevent drift over to non-target plants. 
3. When applying roundup near or in vegetable gardens, increase droplet size to minimize mist and possible drift.