I visited a lima bean field in the Delta at the beginning of June. The beans were showing what appeared to be dampening off symptoms (Figure 1), and dying plants were leaving large gaps down the rows. The problem was pretty widespread throughout the field. Two rows of beans were planted down 60-inch beds with a single drip line buried down the middle of the beds, at about 10-12 inch depth. The soil classification is a mucky clay. While the beans were planted in May, the grower admitted that the soil was still perhaps a bit cool for planting beans (48-52⁰F). (Ideally, we would wait for the soil temperature to reach 65-70⁰F before planting limas.) Additionally, the seed was planted quite deep (4-5 inches), when it probably should have only been planted 1-2 inches deep, provided good moisture in the seedbed. With these conditions, my tentative diagnosis was Rhizoctonia solani because of the reddish-brown lesions I was seeing on the roots. Usually, a seed treatment helps mitigate or control these types of seedling diseases. The grower and I checked a bag of extra seed in the barn, and there was a fungicide seed treatment on the seed.

I sent plant samples to the UC Davis Plant Pathology Diagnostics lab for confirmation on disease. Rather than Rhizoctonia, the lab identified Fusarium oxysporum on all of the plant tissue submitted. While Fusarium oxysporum is the causal agent of Fusarium wilt (a.k.a. Fusarium yellows), the symptoms on these plants indicated root and crown rot, and NOT yellows. Fusarium root rot is common on other beans; however, it has not been a common problem in California limas. For this particular field, its cropping history has been various vegetables for the last couple years, including tomatoes with a severe Fusarium problem in 2016. Rotating out of beans or vegetables to grains would be a good management strategy for future years because Fusarium can live in the soil for several years. Fungicide seed treatments may also help. In this particular case, we talked about managing water well to try to avoid moisture stress (too much or too little) of the current crop to optimize the crop that is there. The grower and PCA assured me that they can manage the moisture well with the drip irrigation on this soil type.  For future bean planting, waiting until soil temperature is warmer and not planting as deep would also be important strategies.

A field in Sutter County was confirmed to have charcoal rot, also known as dry root rot or ashy stem blight, which is caused by the fungus Macrophomina phaseolina.  The disease generally occurs under dry soil conditions paired with high temperatures and can be especially problematic when irrigation is delayed during periods of drought stress. This pathogen infects the crown and stem of garbanzo plants near the soil line and produces black cankers, which are sunken with distinct margins and often contain concentric rings. The disease is usually scattered in the field and often occurs during the flowering and pod stages (although infection can occur at all growth stages). The pathogen infects the stems of seedlings at the base of the developing cotyledon near the soil line. In older plants, symptoms include stunting, leaf chlorosis, early defoliation, and ultimately plant death. A sudden drying of whole plants scattered in the field is observed. Additionally, a “charcoal dust” can appear near the soil line on the surface of roots and stems of older plants. Canker development may kill the plant's growing tip and weaken the stem, causing stems to break, separating roots from the rest of the plant when plants are removed from the field. Infection can move into the hypocotyl and root region, as well as primary leaf petioles. The plant taproot often becomes dark, necrotic, and devoid of lateral and fine roots. 

 

 

 

The Diseases and Abiotic Disorders section of the UC IPM Pest Management Guidelines for Dry Beans have been recently revised and updated and are now available online at UC IPM Dry Beans Pest Management Guidelines.

Authors include Farm Advisors Carol Frate (emeritus) and Rachael Long and UC Davis Professor Paul Gepts. Two new diseases were added, including pythium in established plants and chocolate blotch on limas.  The Fusarium wilt sections were also consolidated and new photos were added throughout the guidelines.  This includes an updated photo page to compare common diseases and abiotic symptoms to help identify them (Photo Identification). 

With the upcoming planting season for dry beans, these guidelines can help with managing diseases in your fields. Worried about southern blight? Yes, beans are susceptible and you'll need to rotate to a non-host crop, including corn or grains for at least 2-years to reduce the inoculum. How about alfalfa mosaic virus? This disease is transmitted by aphids from alfalfa fields, so avoid planting beans adjacent to alfalfa. This information and much more are available through the revised UC IPM Dry Bean guidelines! 

The remaining pest management sections, including insect pest and weed management, are in the process of being revised and will be published soon! 

The UC Agriculture and Natural Resources Agricultural Issues Center (UC ANR) has released two new studies on the costs and returns of producing garbanzo beans (chickpeas), in the Sacramento and San Joaquin Valleys. Although acreage is relatively small (about 10,000 acres), garbanzos are an important crop because California growers produce the large, cream-colored seed for the canning industry. Canned garbanzos are often used for garnishes for salads. 

The studies estimate the cost of producing garbanzo beans on 200 acres as part of a row crop rotation, using sub-surface drip irrigation. A 3-row bed tillage implement shallowly chisels, tills and re-shapes the beds, avoiding disturbance of the buried drip tape left in place. Planting of treated seed (for fungal and seedling diseases, Ascochyta rabiei, Rhizoctonia and Pythium), into residual soil moisture occurs in December. Seeding rates for the garbanzo beans are 85 pounds per acre.

Input and reviews were provided by UC ANR Cooperative Extension Farm Advisors and other agricultural associates. Current costs for the garbanzo bean crop were used, including material inputs, cash and non-cash overhead. A ranging analysis table shows profits over a range of prices and yields. Other tables show the monthly cash costs, the costs and returns per acre, hourly equipment costs, and the whole farm annual equipment, investment and business overhead costs.

The importance of these studies right now is that they are currently being used to help secure USDA crop insurance for garbanzo production, expected in 2020.

The new studies are titled: “Sample Costs to Produce Garbanzo Beans (Chickpeas), in the Sacramento and Northern San Joaquin Valleys – 2018”

“Sample Costs to Produce Garbanzo Beans (Chickpeas), in the Southern San Joaquin Valley – 2018

These studies and other sample cost of production studies for many commodities are available through UC ANR They can be downloaded from the UC Davis Department of Agricultural and Resource Economics website at http://coststudies.ucdavis.edu.

For additional information or an explanation of the calculations used in the studies, contact the Agricultural Issues Center at (530) 752-4651 or the local UCCE Farm Advisors; Sarah Light, selight@ucanr.edu, Rachael Long, rflong@ucanr.edu, Michelle Leinfelder-Miles, mmleinfeldermiles@ucanr.edu, or Nicholas E. Clark, neclark@ucanr.edu.