Fall Lima Bean Harvest

October 13, 2011 in Uncategorized

Lima bean harvest continues in the county through the month of October.  It has been a tough year for lima beans in Kent County as the early planted crop went through extreme heat and drought causing abscission of flowers and pods.  Many of the June planted lima beans had split sets.  Growing conditions have been more favorable for July planted lima beans, though Hurricane Irene dumped up to eleven inches of rain causing some damage.  September’s wet and cool weather provided optimum conditions for downy mildew development, pressuring growers to make several fungicide application.  While early planted lima beans suffered and resulted in very low yields, the late planted lima beans are finishing with better yields.  

Pod-stripping Combines harvest lima beans from a field near Felton, Delaware.  Photo by Phillip Sylvester.

As a side note to the harvest, lima bean growers still have an opportunity to plant a cover crop.  Cereal cover crops such as wheat or rye will help to stabilize the soil, add organic matter, take up excess nitrogen in the fall and carry through to next spring, and provide some weed suppression.  Rye in particular is likely to do best late planted.  Plan to seed before the end of the month so adequate fall growth can take place. 

Phillip Sylvester, Extension Agriculture Agent, Kent County, UD

Hot Weather and Lima Beans

August 1, 2011 in Uncategorized

Recent weather conditions have been very warm and dry with some scattered thundershowers.  Daytime temperatures have been topping out in the 90’s (18 days over 90 in Dover area in the month of July).  Below is information on how lima beans respond to high temperatures and low soil moisture:

Many factors influence lima bean yields, but weather conditions that affect flower bud development, pollination, and pod maturation have the most impact on yields in Delaware. Low lima bean yields are associated with profuse abscission of flowers and developing pods. Research conducted at the University of Delaware in the 1970s revealed that high temperatures, low relative humidity, and low soil moisture lead to reduced pod set and retention. Temperatures of 90 degrees Fahrenheit or above reduce pollination and pod set. Prolonged drought (7 days or more with less than 1 inch of water) also negatively affects yield. High humidity favors pollination and pod set and is one reason lima beans have been grown successfully in Delaware. Fogs, heavy dews, and their moderating effects on temperature are helpful to pollination and pod set. High night temperatures also adversely affect yields, because energy is consumed through respiration, thereby limiting the plants physiological ability to set and retain pods.

Lima bean flower are produced on an indeterminate raceme; three flowers appear at each node along the raceme. Recent research conducted at The University of Delaware identified important phenomena related to flowering. The two outer flowers at each node begin to develop simultaneously, while the middle structure lagged in development. If one or both of the outer structures abscised, the middle structure continued to develop, but at a greater rate than when the outer two flowers continued to develop into fruit. In Delaware, this “reflowering” contributed very little to final yield, while concurrent studies in California found that re-flowering accounted for up to 75 percent of the final pod set.

This helps explain the consistently higher yields in California (4,000 pounds/acre versus a state average of 1,800 in Delaware). Cool nights in California also play a role in allowing the plant to perform at higher levels of efficiency. Interestingly, Delaware yields generally increase with later planting dates, which correspond to both higher rainfall, cooler day temperatures, and cooler night temperatures in September and October, at a time when later plantings are flowering and setting pod.

Depending on variety, first flowering generally occurs at 35 days from planting, and peak flowering at 60 days; harvest occurs from 80 to 90 days for baby varieties, and 90 to 100 days for Fordhook varieties. However, a wide range of factors can influence maturity, including temperature, drought, and any environmental conditions that cause a prolonged flowering period (split-set).

From Successful Lima Bean Production in Delaware.  Ed Kee, James Glancey, and Tracy Wooten.  VF-6. University of Delaware Cooperative Extension. 

Lima Bean Planting Time

May 26, 2011 in Uncategorized

Baby lima bean planting has begun in the county.  Plantings will continue into small grain harvest and will end sometime in July.  Lima beans are planted in 30 to 36 inch rows and growers should shoot to have 3 to 4 plants per foot.  A yard stick can be used at planting to count the seeds in 36 inches and divide by 3. Plant 50 lbs per acre, 1.5 inches deep, unless the soil is dry which warrants deeper planting.  For irrigated fields, row spacing should be 18 to 30 inches apart with 4 to 5 inches between plants.  Plant between 76 pounds per acre at wider spacing and 96 pounds per acre at close spacing.  For growers planting the Fordhook Type this year, rows should be 30-36 inches apart with 2 plants per foot.  Plant 85 pounds per acre, 1.5 inches deep.
Lima beans require between 60-80 pounds of nitrogen.  If lima beans are planted after peas, nitrogen rates should be reduced.  Growers should consider splitting nitrogen applications, 30-40 pounds at planting and another 30-40 lbs 3-5 weeks after emergence.  This can be especially beneficial if heavy rainfall occurs after planting which can leach the nitrogen applied at-planting.

Phillip Sylvester, Extension Agricultural Agent, UD, Kent County.  Information from 2011 Delaware Commercial Vegetable Production Recommendations.

Nitrogen Deficiency in Lima Beans

July 13, 2009 in Uncategorized

I recently looked at several plantings of processing lima beans as well as pole lima beans showing nitrogen deficiency. The following is more information.

Both early planted processing baby lima beans and market garden pole lima beans are showing signs of nitrogen deficiency now across the state, even with adequate N being applied. This is likely a result of excessive N leaching during the wet spring periods in May and early June in many fields, especially on very sandy soils. Pole lima beans commonly show N deficiencies later in mid-summer as pod set and development progresses; however this year, yellow plants are being seen much earlier.

Severe N deficiency in lima beans will be seen as an overall yellowing of plants with lower leaves often dropping off as N is mobilized from the oldest leaves to support the new growth at growing tips. Less severe N deficiency will be seen as a lighter green color than normal with lowest leaves most affected. Tissue tests can be used to confirm N deficiencies. Take the uppermost fully expanded leaves to send off for analysis. There are other potential causes for yellowing in lima beans including low pH leading to magnesium deficiencies and excessively high pH leading to micronutrient deficiencies, most commonly manganese.

It is important to apply additional N as soon as possible in N deficient lima beans. General recommendations are to sidedress 30-40 lbs of N, 3-5 weeks after emergence in baby lima beans and at early pod set in pole lima beans. In fields that have suffered heavy leaching losses, this may need to be increased slightly. However, remember that too much N can lead to excessive vine growth and delay flowering and pod set. Deficient pole lima beans will need an early sidedress application now and will likely need an additional sidedressing of N in August during pod development.

Gordon Johnson, Extension Agriculture Agent, UD

Early Processing Lima Beans

May 15, 2009 in Uncategorized

The following is information on early processing lima beans.

The earliest processing lima beans will be planted starting in the next 10 days. May planted lima beans often have a lower yield potential than June and early July plantings due to a number of factors. Soil conditions may be cold and this delays germination and reduces stands. Minimum soil temperature for best germination is 65°F. Soil borne diseases such as Rhizoctonia and Fusarium can become established on plant roots, especially when they are growing slowly in cold soils, limiting later yield potential of these early planted lima beans. Heavy infestations of seed corn maggot can overwhelm seed treatments in cold, wet soils reducing stands.

The major limiting factor for early lima beans is the fact that they flower and set pods during summer conditions when day and night temperatures are high. Low lima bean yields in early plantings are associated with high levels of flower and pod drop. Hot, dry weather in July and August will lead to reduced pod set and retention. Day temperatures of 90°F or above reduces pollination and pod set and night temperatures in the 70’s or higher will also adversely affect yields because higher levels of carbohydrates are consumed in night respiration, limiting the plants ability to set and retain pods. Plants may reflower when cooler conditions recur leading to split sets.

The following are some considerations for early lima bean plantings:

• Plant in fields with light soils that heat up quickly and where emergence will not be delayed. Conventional tillage is required for early plantings to speed this warming.
• Plant on a warming trend when soils are 65°F or higher.
• Consider using an additional fungicide treatment for Rhizoctonia control (Ridomil Gold PC or Quadris).
• Choose fields carefully. Fields closer to water bodies were temperatures are moderated by fog, heavy dew, high humidity, and cooling breezes during summer are good candidates.
• Irrigate early planted fields paying particular attention to the flowering and early pod set period. Daytime irrigation can also help to moderate high temperature effects during hot summer periods. It is critical to keep early planted lima bean plants from being water stressed during this period. Do not plant early lima beans dryland.

Although success in early lima bean plantings can be improved by following these suggestions, if there are extended periods with day temperatures in the 90’s and night temperatures in the high 70’s, yields will still be limited.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Split Sets in Dryland Lima Beans

October 5, 2008 in Uncategorized

We are seeing some severe split sets in dryland lima beans this year. Those dryland limas planted in late June and early July produced a poor set in August when plants were essentially shut down by the drought. This was most evident in plantings on lighter soils. When rains came in early September, vine growth resumed but re-flowering did not occur immediately. With additional rainfall from the recent Nor’easter, plants are now reflowering. The following are some pictures I took from a field this past Friday that has this problem – split set with delayed re-flowering.

Gordon Johnson, Extension Agricultural Agent, UD, Kent County

Irrigating Lima Beans

July 25, 2008 in Uncategorized

There is considerable controversy about when and how to irrigate processing lima beans for best yields. The following is an article on the subject.

Past research has shown that irrigated lima beans significantly out-yield dry land lima beans and top yields generally come from irrigated fields. However, when and how much to irrigate is still a question as is the need to irrigate late in the season for fall harvested lima beans.

Research has suggested that irrigating when soil moisture drops to 50% of field capacity gives better yields than letting the soil dry out further for lima beans. It is also better to irrigate throughout the season rather than just from full flowering onward.

To complicate matters, over-irrigation, especially during pod development when there are very dense vines, increases the potential for pod diseases such as Sclerotinia white mold, Lima Bean Pod Blight (Phytophthora capsici), Pythium blight, and Downy Mildew and can lead to significant yield losses. A balance must be maintained between providing needed water and allowing the crop to dry out to reduce disease pressure later in crop development.

It is also important to consider temperature. The following is from Ed Kee during a heat wave in 2006: “The tremendous heat we’re experiencing makes irrigation of lima beans more critical. Blossom drop occurs when the plant is stressed, and even with adequate irrigation blossoms will abort with high temperatures. However, maintaining soil moisture is important to keep the plant cool, which alleviates stress and reduces blossom and pod drop. Lima beans will use 0.25 inches of water per day through evapotranspiration when temperatures are in the nineties. Reducing plant stress as much as possible will help in the retention of “pins” (small pods) and larger pods.”

In lima beans, first flowering generally occurs at 35 days from planting, and peak flowering at 60 days. Providing adequate water with irrigation during the entire flowering period and through pod set is critical for developing and maintaining yield.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Pole Lima Beans – Summer Problems

July 6, 2008 in Uncategorized

Pole lima beans are a very profitable crop for market gardeners across Delaware. However, a number of problems can come up in summer that can limit yield potentials. Some information follows.

  • Heat is the major factor in reducing yields in pole lima beans. Hot days and especially hot nights will cause flower and small pod abortion and reduced summer pod sets. It will also cause reduced seed numbers in pods or pods with underdeveloped seeds (flat pods). This is especially a factor in large seeded pole lima bean types (Dr. Martins). One strategy to partially avoid this problem is to plant as early as practical in May using plastic mulches to warm soils and providing protection to plants against cold snaps using covers. Early and quick starts will allow for plants to mature and set pods quickly and get some July and early August production before heat really starts to reduce sets. Irrigation is critical so that plants are not under any water stress. Misting plants with low volume sprinklers during the middle of the day may help but also sets up conditions for downy mildew.
  • Stink bugs and tarnished plant bugs are a major problem in many areas of the state and can reduce lima bean yields significantly. We have seen an increase of stink bugs in recent years. Stink bugs and tarnished plant bugs pierce young pods with their needle-like stylets, sucking sap out of the pods/young seeds. This causes misshapen seeds or if severe enough, pod drop. Insecticide sprays are used for control including a number of pyrethroids. Be careful with some of the pyrethroids because they can cause mite populations to explode by reducing natural controls (predators). See the Commercial Vegetable Recommendation book for recommended products (link here). Options are limited for non-commercial producers.
  • Two-spotted spider mites will build up in hot dry weather and can cause leaf bronzing and leaf drop if severe by feeding in leaves with piercing/sucking mouthparts. The key to reducing mite injury is proper irrigation to keep plants healthy. Mite control materials are available but are limited. See the Commercial Vegetable Recommendation Book for recommended products (link here). Mite control options for non-commercial producers are very limited.
  • In late July through August, pole lima beans often start to yellow because they are running out of nitrogen. Even though lima beans are legumes, we grow them using nitrogen fertilizers because they tend not to produce enough nitrogen with the nitrogen fixing bacteria. An August side-dressing of nitrogen fertilizer will be necessary often to keep these vigorous vining plants growing.
  • Pod feeding insects such as European Corn Borer and Corn Earworm can be problems and may have to be controlled with insecticides.
  • Other insect pests such as thrips, Mexican bean beetle, and leafhoppers can be problems at times.
  • The major summer disease problems in pole lima beans are downy mildew when the weather is wet, as well as occasional outbreaks of anthracnose and Phomopsis pod blight. Keep informed by reading the Weekly Crop Update on the potential for downy mildew and start controls if advised that weather conditions are favorable.
  • Air pollution can cause bronzing of lima beans in hot, stagnant conditions with air inversions or in areas with a lot of traffic.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County

Overhead Irrigation of Vegetables

May 3, 2008 in Uncategorized

Irrigation is a critical management tool for producing high yielding and high quality vegetable crops. The following is an article on the subject.

Scheduling irrigation for different vegetables grown under center pivot, travelling gun, or solid set overhead systems involves knowledge of the soil water holding capacity, the effective rooting depth of the crop (how deep water can be drawn by the crop), how efficiently water is being delivered (water losses to evaporation before it reaches the crop and how much water is lost to runoff), how much water is being used by the crop (transpiration) and how much water is being lost from the soil and wetted surfaces directly (evaporation). The combination of transpiration and evaporation losses is termed evapotranspiration.

To schedule irrigation, the goal is to replace water lost through evapotranspiration without excessive runoff or excessive loss through drainage out of the root zone. Another factor to consider is the permissible water depletion; how much will you allow the soil to dry down between irrigations. For most crops we set this at 50% of the water holding capacity of the soil. However, for some shallow rooted crops you may want to keep that value lower (only allow for 40% depletion between irrigations). By knowing how much water is being lost and how much is left in the soil, you can determine when to irrigate and how much to irrigate.

In classic work done by the University of Delaware Agriculture Engineering Department in the 1970s and 1980s, water use estimates were developed for a number of vegetable crops. These values remain useful guides for irrigating these crops. A summary follows:

Sweet Corn: Water use 40 days after planting was 0.10 inches per day, water use 60 days after planting was 0.23 inches per day and water use at peak (75 days) was 0.26 inches per day.

Potatoes: Water use 40 days after planting was 0.15 inches per day, water use 60 days after planting was 0.27 inches per day and water use at peak (80 days) was 0.37 inches per day.

Peas: Water use 40 days after planting was 0.16 inches per day and water use 60 days after planting was 0.33 inches per day (peak).

Lima Beans: Water use 20 days after planting was 0.13 inches per day, water use 40 days after planting was 0.25 inches per day, water use 60 days after planting (peak) was 0.33 inches per day and water use 80 days after planting was 0.23 inches per day.

Cucumbers: Water use 20 days after planting was 0.13 inches per day, water use 40 days after planting was 0.27 inches per day, and water use at peak (50 days) was 0.30 inches per day.

Watermelons: Water use 20 days after planting was 0.10 inches per day, water use 40 days after planting was 0.23 inches per day, water use 60 days after planting (peak) was 0.30 inches per day, water use 80 days after planting was 0.28 inches per day and water use 100 days after planting was 0.22 inches per day.

Tomatoes: Water use 20 days after planting was 0.15 inches per day, water use 40 days after planting was 0.27 inches per day, water use 60 days after planting (peak) was 0.33 inches per day, water use 80 days after planting was 0.28 inches per day and water use 100 days after planting was 0.25 inches per day.

Gordon Johnson, Extension Agriculture Agent, UD, Kent County