Posts Tagged ‘lima bean’

Lima Bean Downy Mildew Season Ahead

Friday, August 24th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

The following was modified from a 2011 article from Bob Mulrooney, Extension Plant Pathologist (now retired), University of Delaware

As we move into late August and September, cooler temperatures, heavy dews and fogs, and the potential for heavy rains from tropical storms can be favorable for development of downy mildew in lima beans. Conditions are most favorable when fields receive 1.2 inches or more of rain within 7 days and when average daily temperature during this period is 78°F or less (heavy dews and fogs reduce the amount of rainfall necessary to start infection). Temperatures over 90°F will break the infection cycle. Lima bean fields should be scouted in the next 4 weeks for the presence of downy mildew as well as white mold. Race F of Phythophthora phaseoli was the only race of downy mildew identified from 2008 to 2011.

Preventative applications of 2 lbs fixed copper such as Kocide 3000 (1.3 lbs/A), Champ DP, or other coppers; 2 lbs Ridomil Gold/Copper; or 3- 4 pts Prophyt have provided control of downy mildew in the past. The best controls continue to be Ridomil/Gold Copper, and Prophyt, or other labeled phosphonate fungicides when disease pressure is high. Application at flowering or when pods are first forming is recommended if weather is favorable for disease. If disease is present Ridomil/Gold Copper and phosphonate fungicides have shown to provide some curative activity if applied when downy mildew is first seen. If downy is present in the field do not use copper fungicides alone for curative control, they will not provide control. Another product that is labeled on lima beans for white mold control is Omega and while not specifically labeled for downy mildew, three years of data has shown that it has excellent control of downy mildew at 5.5 fl oz and 8.0 fl oz/A as a preventative application before disease is found in the field. In DE this would be a 2ee use since the fungicide is labeled on lima beans and is appropriate where a mix of white mold and downy mildew are in the field. Omega has a 30 day preharvest interval. Headline from BASF is also labeled for downy mildew. It has been tested in Delaware and it has provided good control of downy when applied on a 10 day schedule at 6.0 fl oz. /A. It does not give as good disease control as Ridomil Gold/Copper or the phosphonates preventatively but the yields have been comparable. It is also labeled for anthracnose which the other products do not control. See the 2012 DE Commercial Vegetable Production Recommendations for more information on fungicides for lima beans.

We would appreciate samples and reports of lima bean downy mildew this season. Samples should be fresh and packaged in a zip lock plastic bag with dry paper towels. Samples can be dropped off at any of the county Extension offices or delivered directly to Nancy Gregory at Townsend Hall in Newark. Reports should be made to Nancy Gregory at ngregory@udel.edu.

Heat Affects Early Lima Beans

Friday, July 27th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

We are seeing heat effects on early planted lima beans again in 2012, with heavy bud, blossom, and pod drop. A split set is also present because of changes from high heat where pod set was limited to more moderate temperatures favoring pod set back to high heat again causing pod loss. Another problem is misshapen pods and irregular, dimpled, or misshapen seed which may be caused by incomplete pollination due to the heat or direct piercing/sucking insect damage to the seed.

Weed Control for Succulent Beans

Friday, June 22nd, 2012

Mark VanGessel, Extension Weed Specialist; mjv@udel.edu

There is some overlap of herbicide options for snap beans and lima beans, but growers need to pay particular attention that a product is labeled for snaps or lima beans and do not assume if it is labeled for one, it is labeled for both. One thing that is consistent for both lima and snap beans is that postemergence herbicides need to be applied to small weed seedlings (3 inches tall or less).

Snap Beans
Weed control in snap beans starts with a good soil-applied program. The regional recommendations include Eptam, Treflan or Prowl, applied pre-plant incorporated; Dual, which can be applied preemergence or pre-plant incorporated; or Command or Sandea applied preemergence. Early postemergence treatments for broadleaf weeds include Basagran, Reflex, or Sandea. Select Max, Targa/Assure II, or Poast are labeled for postemergence grass control. UD research has seen consistent control with Dual used at planting followed by a timely (1 to 2 trifoliate stage of the beans) application of Reflex and Basagran. If there are concerns about timely application of the postemergence herbicides, consider use of a broadleaf weed herbicide at planting.

Lima Beans
The biggest difference from snap bean herbicides is Reflex. Snap beans tolerate Reflex quite well, but lima beans are very sensitive to Reflex. In fact, Reflex applied earlier in the season then lima beans planted as a second crop can also result in lima bean injury. A soil-applied herbicide program for lima beans is very important due to the lack of effective postemergence herbicides. Herbicides listed in the regional vegetable guide for lima beans include:

Pre-plant incorporated: Prowl or Treflan

Pre-plant incorporated or preemergence: Dual or Pursuit

Preemergence only: Sandea or Spartan Charge (only labeled in DE)

Postemergence: Basagran or Raptor for broadleaf weeds; Select Max or Poast for grasses.

Early Planted Lima Beans

Thursday, May 24th, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Lima bean planting has begun in the region. With the expected warming trend, there is good potential for rapid germination and emergence this year due to higher soil temperatures. It is interesting to note that the variety Cypress was bred for good emergence under cooler planting conditions in Canada. We planted a trial using Cypress the first week in May this year and had excellent germination and emergence. We will harvest this trial the last week in July and then allow it to regrow and harvest a second time from the regrowth in October. Unfortunately, Cypress is very susceptible to pod drop due to heat. May planted lima beans, both at our research station and on growers farms in 2011 had very poor yields in the summer due to severe pod drop, even though some fields were well irrigated.

This illustrates the problem with May and early June planted lima beans: they most often have a lower yield potential than late June and early July plantings because they flower and set pods during summer conditions when day and night temperatures are high. Day temperatures greater than 90°F cause stomates to close early during the day to limit water loss, reducing lima bean photosynthesis. This results in fewer pods being carried by the plant. Night temperatures in the 70s 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 will reflower when cooler conditions recur, but this may lead to split sets.

Unfortunately, until more heat tolerant varieties are available (at the University of Delaware, one of our lima bean breeding objectives is to select for greater heat tolerance) , growers are limited in what they can do to maintain yields in early lima bean plantings. Fields closer to water bodies were temperatures are moderated by fog, heavy dew, high humidity, and cooling breezes during summer are the best candidates for early plantings. In addition, irrigate early planted fields, paying particular attention to the flowering and early pod set period and do not plant early lima beans dryland. 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.

Processing Acres Up This Year

Friday, March 2nd, 2012

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Processing vegetable acres will be up this year in Delaware and on Delmarva including peas, lima beans, and sweet corn. Pickle acreage will remain steady. This increase in acres is largely due to reduction in stocks. For example, for lima beans, cold storage stocks in January 2011 were 58 million pounds and in January 2012 these stocks were down to 44 million pounds. Peas were down from 234 to 210 million pounds and sweet corn was down from 521 to 436 million pounds. This drop in sweet corn stocks is a major driver in picking up acres. It is interesting to note that in 2011, Delmarva lima bean acres were close to 19,000. This represented over 60% of the US acres and 40% of the production. California acres are down due to competition for land with more profitable crops.

Vegetable Disease Update – September 23, 2011

Friday, September 23rd, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Lima Bean Downy Mildew
Downy mildew is present now in Delaware lima bean fields. Levels are not high but many have been sprayed to protect the crop. Keep scouting and apply fungicides when needed; see past issues and the 2011 Delaware Commercial Production Recommendations for more information.

Fall Sanitation
In vegetable production it is not a good idea to leave old crop residue in the field any longer than necessary. If the crop is allowed to survive after harvest, fungi that cause many diseases continue to increase on the surviving plants. This allows higher numbers of the fungus to potentially survive until next season. Sanitation (plowing or disking the old crop) will help prevent pathogen carry-over.

Nematodes in Veggies
Fall is the best time to soil sample for nematode pests such as root knot, lesion, and other plant parasitic nematodes. After fall harvest but before any fall tillage is done take soil cores six inches deep between plants in the row. Samples should be taken in the root zone of the old crop. Twenty cores/ sample should be taken from random spots in the field and placed in a plastic bucket gently mixed, and a pint of soil submitted for analysis. Large fields should be subdivided into blocks of 10-15 acres each and sampled separately. Nematodes are not uniformly distributed in the soil and it would be easy to miss significant numbers if a single sample of 20- 25 soil cores represented a large acreage. Nematode test bags and instructions are available for purchase from the county Extension offices. Samples cost $10.00. Fall sampling for root knot nematodes is strongly recommended for fields that will be planted in cucumbers, watermelons, cantaloupes, lima beans or other high value vegetables where root knot could reduce production. Forms and instructions are also available on the web at http://ag.udel.edu/extension/pdc/index.htm.

New video on nematode sampling
“How to Sample for Nematodes”
is a new video that was just produced to help growers with taking nematode samples in the fall to monitor plant parasitic nematode populations in their fields. The video features Bob Mulrooney, Extension Plant Pathologist at the University of Delaware explaining and demonstrating how to take soil sample for nematodes in row crops as well as narrow crop soybeans. The link for viewing is on the CANR You Tube server at http://youtu.be/x5HcY_L6aQk.

Delayed Sets in Lima Beans

Friday, September 16th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

In talking with growers and observing our research plots, 2011 was another challenging year for early lima beans. May planted lima beans harvested in late July and in August did produce a partial set with yields ranging from 500-2000 lbs depending on field and location. There was enough cool weather in the second half of June to allow for some set, but July heat did not allow for continued set, even in irrigated conditions

Early June planted lima beans have been a mixed bag, again depending on field and location. Some fields have a bad split set and all the associated problems of when to harvest. However, many early June planted fields dropped all their early sets due to the mid-summer heat, retaining pods only after the heat abated, thus delaying harvest 2-3 weeks (from expected late August to mid September). These fields are yielding much better (over 3000 lbs irrigated). Fields planted later in June and in July did lose some set due to wind damage during the hurricane but have recovered well and the impact on yield may be minimal, although harvest will be pushed later in some fields.

On another note, the regrowth cropping lima bean trial on our research farm, initially harvested in late July, has a good set and will make a second crop long before frost. Observations from other growers experimenting with regrowth cropping are similar, with good regrowth and set where wheel traffic at harvest was not severe.

Vegetable Disease Update – September 16, 2011

Friday, September 16th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

Lima bean downy mildew was found by a CCA and confirmed on Wednesday from a field of ‘C-elite’ near Galena, MD. Growers need to be scouting carefully and applying fungicides as needed. If seen in the field apply either Ridomil Gold/Copper 2.0 lbs/A or ProPhyt (3.0 pts/A). See the 2011 Delaware Commercial Vegetable Production Recommendations for other fungicide choices as well as last week’s WCU for more detailed information.

Basil downy mildew was found in New Castle County this week. Any specialty crops growers might want to protect basil with one of the phosphorus acid products, such a ProPhyt, at this time.

Powdery and downy mildew are widespread in cucurbits especially pumpkins and winter squash at this time. Maintain fungicide programs until fruit develop fully.

Unfortunately Phytophthora fruit rot is very prevalent on a number of cucurbits especially pumpkin at this time. The excessive rainfall just made a bad problem worse. A few growers have asked about dipping fruit in a 5-10% bleach solution or using Zerotol to prevent fruit rot. My experience has been that is not effective if the fruit are infected in the field. You may get reduced spread in a bin but it will not control Phytophthora fruit rot.

There were a few reports of late blight in New York and Connecticut this week, but nothing in the Mid-Atlantic to worry tomato growers so far. To track the progress of late blight in the US you can go to http://usablight.org

Wet Weather Lima Bean Issues

Friday, September 9th, 2011

Gordon Johnson, Extension Vegetable & Fruit Specialist; gcjohn@udel.edu

Due to the wet conditions, lima bean growers are reminded to check all fields for downy mildew and white mold. Phytophthora capsici and Pythium also may be present and can confuse diagnoses. Consult with your extension pathology specialists, county agents, or state disease diagnosis personnel for correct identification. As harvest nears, note days to harvest if fungicides are to be applied. See additional articles for identification and control of these diseases.

The main fall lima bean harvest is starting. However, harvest is being hampered by wet conditions. Rain and wet fields at harvest lead to several issues that growers will face.

The first issue is brown beans. Many of our June planted fields had variable and partially split sets. This means that there are higher numbers of dry pods on the plants. In dry harvest conditions, these dry seeds can be harvested, separated, and processed. However, during wet weather, dry seeds will start to deteriorate and will turn brown. This makes processing more difficult due to the necessity of removing them.

In addition, because of recent storms where plants or have lodged and more branches are touching the ground, many of the dried pods will rot, leading to rotted seeds that must be removed.

A third issue is seed sprouting. In recent plot harvests, I have seed small but significant numbers of seeds that have started to sprout. Again these must be removed during processing.

Finally, as harvest resumes, wet field conditions along with harvester and truck traffic on fields will lead to more rutting and compaction that will need to be addressed in future cropping cycles.

Weather Conducive for a Host of Lima Diseases

Friday, September 9th, 2011

Bob Mulrooney, Extension Plant Pathologist; bobmul@udel.edu

The recent heavy rainfall from the storms has been very favorable for development of downy mildew. Lima bean fields should be scouted carefully now for the presence of downy mildew as well as white mold. The weather has also raised the possibility of seeing gray mold (Botrytis). Race F of Phythophthora phaseoli was the only race of downy mildew identified in 2006, 2008, 2009, and 2010. Preventative applications of 2 lbs. fixed copper, 2 lbs. Ridomil Gold/Copper, or 3- 4 pts. Prophyte have provided control of downy mildew in the past. The newest formulation of fixed copper from DuPont is Kocide 3000 and it performs as well as the other formulations of copper at the rate of 1.3 lbs/A. The best controls continue to be Ridomil/Gold Copper, Prophyt, or other labeled phosphonate fungicides and Omega, especially when disease pressure is high. Application at flowering or when pods are first forming is recommended if weather is favorable for disease. If disease is present Ridomil/Gold Copper and phosphonate fungicides have shown to provide some curative activity if applied when downy mildew is first seen. If downy is present in the field do not use copper fungicides alone for curative control, they will not provide control. Another product that is labeled on lima beans for white mold control is Omega but not downy mildew, but in DE this would be a 2ee use that someone like me can recommend since the fungicide is labeled on lima beans. I have three years data that show excellent control of downy mildew at 5.5 fl oz and 8.0 fl oz/A as a preventative application (before disease is found in the field). Omega is not labeled for aerial application, however. Headline from BASF is also labeled for downy mildew. I have tested it and it has provided good control of downy when applied on a 10 day schedule at 6.0 fl oz. /A. It does not give as good disease control as Ridomil Gold/Copper or the phosphonates preventatively but the yields have been comparable. It is also labeled for anthracnose which the other products do not control. See the 2011 DE Commercial Vegetable Production Recommendations for more information on fungicides for lima beans.


Downy mildew caused by Phytophthora phaseoli


Downy mildew on raceme and petiole

 Phytophthora capsici on lima bean pod.

Phytophthora capsici will infect lima bean pods as well and can look very similar. P. capsici or lima bean pod rot is usually found in wet low spots in the field. The fungus growth looks more granulated or “pebbly” than downy mildew, microscopic confirmation is encouraged.

 

Downy mildew on the upper pod and lima bean pod rot on the lower pod. Note the granular appearance of the fungus on the lower pod and the lack of a reddish brown border on the pod infected with lima bean pod rot or Phytophthora capsici.