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. 

Charcoal rot on garb root (left), healthy garb root (right)

Garbanzo field with charcoal rot

Garbanzo field with charcoal rot

Management options in California are limited. This disease affects other legumes like common beans, blackeyes, and limas, as well as other crops that may be grown in rotation (like sunflowers). Inoculum survives in both seeds and soil. A 3-year rotation with a cereal grain (except corn and sorghum, which are hosts) is recommended to reduce soil inoculum levels. The dry, warm weather in the winter months earlier this year were conducive to drought stress for garbanzos, which increased the risk of disease. If possible, irrigate to avoid drought stress conditions. Garbanzos grown in soils that are high in organic matter tend to have more problems with this disease, however, garbanzos in other soil conditions are at risk if the plants are stressed and the environment is conducive to disease development.

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. 

Garbanzo pods and beans.

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.

Harvesting garbanzo beans, Yolo County, 2017.

Ascochyta symptoms on garbanzo leaves.

Ascochyta blight (Ascochyta rabiei, Didymella rabiei) was recently found in volunteer garbanzos in the Sacramento Valley, so keep an eye out for this disease in your production fields and be sure to control all volunteer garbs on your farm (yes, these volunteers are now long gone).

Symptoms

Ascochyta is a serious fungal disease of garbanzos that can kill seedlings and significantly reduce yields and seed quality in older infected plants. There are no other known crop or weed hosts. This disease is favored by cool, rainy weather and only infects the above ground parts of the plants. Early symptoms include circular light brown lesions on the plants that cause stems to weaken and break. Over time small, black, raised spots (pycnidia-like spores) will form concentric rings in the lesions. Developing seeds can become infected and, if used for seed, can lead to early infections in the next crop. The fungus survives outside or inside the seed. 

Characteristic concentric fungal rings on leaves.

Ascochyta fungal rings on pods.

Comments

The fungus survives only on crop debris (and seed), not in soil. It does not produce resting spores to survive in soil. How long the debris can persist before decomposing depends on the climatic conditions. It lasts longer in drier conditions. During wet weather, spores are released and infect plants. Moderate temperatures (68º to 77ºF) and wet weather are optimal conditions for severe disease development. 

Management

• Plant Ascochyta tolerant varieties.
• Keep stands healthy, as disease resistance can break down in stressed fields.
• Always use certified, disease free seed.
• Thoroughly incorporate infested garbanzo residue to hasten decomposition and to minimize the possibility of spore production and dissemination.
• Rotate to other crops for two or three years. That will eliminate inoculum in the soil because the fungus will not survive in the absence of a garbanzo host.
• Avoid early plantings (November and early December) since they result in large plants and a thick canopy, which provides ideal conditions conducive to disease development.
• Consider wide row and plant spacing. This increases ventilation between plants, reducing favorable conditions for plant infection.
• Use treated seed to avoid introducing the fungus to the field, such as Mertect 340-F, thiabendazole.
• Foliar applications of fungicides limit the rate of disease spread. Apply fungicides at first sign of disease and reapply according to the label if rainy weather is forecasted. Thorough coverage of the plant canopy is important. Options include Quadris (azoxystrobin), Endura (boscalid), or Headline (pyraclostrobin).

For more information, refer to the UC IPM website for dry beans or publication 8259, Ascochyta Blight of Garbanzos, by Frate et al. 2007.

Ascochyta infected plants.

White mold in garbanzos often infects the plant stems near the soil line.

Our cool, wet conditions are favoring white mold (sclerotinia) in garbanzo beans this year. This disease is characterized by a white fungal growth that attacks the above ground plant parts, often near the soil line for garbanzos. The affected tissue dries quickly and bleaches to a pale tan or almost white color.  Black sclerotia formed on the stem of dying plants are often visible. These are masses of fungi compacted to form small, dark pellets that range in size from 1-8 mm (about the tip of a pencil to a pencil-size eraser) that allow the fungus to survive in adverse conditions (e.g. hot, dry weather). When the main stem is affected near the soil line, the entire plant wilts and dies; lesser infections will show dead branches, causing yellow flagging in the field.

White mold in garbanzos causes yellow flagging in the field.

The black sclerotia pellets formed in the mold can survive many years in the soil and re-infect crops. The development of white mold is greatly influenced by prevailing weather conditions and certain agronomic practices such as late extensive irrigation, plant density, and plant growth characteristics, which are all closely linked with the life cycle of the pathogen. A thick dense plant growth provides a micro climate of cooler temperatures and high moisture beneath the plant canopy where conditions are favorable for disease.

The best control focuses on cultural practices to prevent the disease from developing in the field. This includes higher beds that keep lower plant parts and tops of the bed drier, wider row spacing to increase air movement in the canopy to keep the foliage drier, and planting garbanzo beans later (December through early February) rather than early (November) since the extra growing time can result in heavy canopies that increase humidity and cause infestations late winter/early spring (favorable disease conditions, 68^oF-77^oF). Crop rotation generally does not prevent white mold infection due to the broad host range of the pathogen.

Fungicides are available for white mold control, but getting good coverage and control is difficult because the inoculum is in the soil and the disease is often deep in the plant canopy. Fungicides would have to be applied when plants are smaller to provide good coverage and protection from this disease. For a list of fungicides available for white mold control in in garbanzos, see http://ipm.ucanr.edu/PMG/r52100111.html.