Now is the time to start thinking about which delicious vegetables you want to grow in your garden. Ted and Rho will go over all the possibilities with you in this class.
Spring Vegetables
These vegetables don't mind the cold and can be planted from seed in February. They may grow slowly, but as weather warms they will grow more quickly. Lettuce, Swiss Chard, arugula, mustard greens, and other leafy greens do well. Radishes, beets, carrots, turnips, and happy during this time as well. However, by late spring/early summer, many of these plants can't take the heat and may “bolt,” sending up flower stalks that the bees enjoy.
Summer Vegetables
You can plant these vegetables from seed or transplant in late March. They prefer warm weather and may “sulk” and grow very slowly if you plant them too early. These vegetables include melons, squash, winter squash, corn, tomatoes, and cucumbers.
Hope to “see” you there!
Where*: On Zoom. You will receive a link the morning of the class.
When: Tuesday, February 22, 2022 6:00-7:30 p.m.
Cost: Free
Register at: http://ucanr.edu/spring/veg/2022
Instructors: Master Gardeners Rho Yare and Ted Hawkins
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- Author: Jeannette E. Warnert
Considered among the most important agricultural innovations in the world, drip irrigation has been researched for decades. UC Cooperative Extension weed management advisor Aliasghar Montazar has taken a close look at its application in organic spinach cultivation, reported Matthew Grassi in Growing Produce.
Not only does drip irrigation use less water than irrigation with sprinklers, the slow emission of water near plant roots also diminishes the crops' susceptibility to disease. Growers believe that ongoing issues with downy mildew is at least partially caused by moisture that sprinklers leave in the plant canopy.
“Being certified organic, there is really nothing they can use as fungicide; so it is a big problem,” Montazar said. “So, we said ‘Let's try drip (irrigation) in spinach.'”
Early results are promising. Montazar has analyzed enough field data from the plots to directly correlate a four- to five-times reduction in downy mildew disease in plots grown with drip irrigation compared to sprinkler-irrigated plots.
“The other thing to note is there is a nice savings on energy as well,” Montazar said. “Another grower reported he saved $200 an acre on energy savings from getting off the sprinklers. Because with drip, there is less pressure needed, so it consumes less energy (to pump water).”
- Author: Aliasghar Montazar
- Author: Michael D Cahn
- Author: Alexander Putman
Spinach is a fast-maturing, cool-season vegetable crop. In California, most conventional and organic spinach fields are irrigated by sprinkler irrigation. However, sprinkler irrigation could contribute to the speed and severity of downy mildew epidemics, as the most important disease in spinach, within a field when other conditions such as temperature are favorable.
Although fungicides are available for the control of downy mildew in conventional production systems, products with similar efficacy are not available for organic spinach. Adapting drip irrigation for high-density spinach plantings may be a possible solution to reduce yield losses from downy mildew and enhance resource-use efficiency in organic spinach production.
Currently, drip irrigation is not used for producing spinach in California, and there is a lack of information on the viability of this technology and optimal practices for irrigating spinach with drips. We initiated a study funded by the California Leafy Greens Research Board to evaluate the viability of drip irrigation for organic spinach production in California. The project was particularly aimed at understanding the system design to successfully produce spinach, and to conduct a preliminary assessment on the impact of drip irrigation on the management of spinach downy mildew.
So far, the experiment has been conducted over two crop seasons at the University of California Desert Research and Extension Center located in the low desert of California. Various combinations of dripline spacings and installation depths were assessed and compared with sprinkler irrigation as control treatment. Comprehensive data collection was carried out to fully understand the differences between the irrigation treatments.
Statistical analysis indicated very strong evidence for an overall effect of the irrigation system on spinach fresh yields, while the number of drip lines in bed had a significant impact on the shoot biomass yield. The developed canopy crop curves revealed that the leaf density of drip irrigation treatments was slightly behind (1–4 days, depending on the irrigation treatment and crop season) that of the sprinkler irrigation treatment in time.
The results also demonstrated an overall effect of irrigation treatment on downy mildew, in which downy mildew incidence was lower (approximately 5 times lower) in plots irrigated by drip following emergence when compared to the sprinkler. The likely mechanism causing this effect was a reduction under drip irrigation of leaf wetness, which is critical for infection and sporulation by the downy mildew pathogen.
The probe output of the leaf wetness sensors for a period of 12-day showed that sprinkler-irrigated crop canopies remained wet 24.3% times longer than the crop canopy irrigated by drip system. The preliminary findings: drip irrigation has the potential to be used to produce organic spinach, conserve water, enhance the efficiency of water use, and manage downy mildew, but further work is required to optimize system design, irrigation and nitrogen management practices, as well as strategies to maintain productivity and economic viability of utilizing drip irrigation for spinach. Assessing drip irrigation for the entire crop season, including germination, could be another research interest since spinach is a short-season crop and combining the sprinkler for crop germination and drip for such a short period might cause some practical issues. We will continue investigating these issues through this ongoing project in the next two years.
For more information about the results of this project so far, you may view the recently published research article in MDPI, Research Advances in Adopting Drip Irrigation for California Organic Spinach: Preliminary Findings
This article was also published in the August-September 2019 issue of Organic Farmer magazine.
- Author: Richard Smith
- Author: Steven Fennimore
- Posted by: Gale Perez
Spinach is susceptible to weed pressure because it is produced on high-density 80-inch wide beds with 18 to 42 seedlines. There is no opportunity to cultivate the bed top so all weed control is accomplished by managing weeds in prior rotations, cultural practices, chemical weed control or hand weeding. Clipped spinach is mechanically harvested and must be kept as weed free as possible to reduce hand weeding costs. In the recent UC publication, Sample costs to produce and harvest organic spinach (Tourte et al, 2015 http://coststudies.ucdavis.edu/current/ ) hand weeding costs averaged $440 per acre. However, weeding costs can easily exceed $1,000 per acre in weedy fields, and if cost get to high, growers may decide to disc the field. A key factor that affects weeding pressure in spinach fields is the prior crop. Long-season crops such as peppers, annual artichokes and leeks tend to allow more weed seed set and can increase weeding costs in a subsequent crop like spinach.
RoNeet and Dual Magnum are registered preemergent herbicides for use on spinach. RoNeet is the most commonly used preemergent herbicide on spinach; it is volatile and must be quickly incorporated into the soil for best efficacy. Post planting, preemergent applications are typically incorporated with sprinkler irrigation, but it can also be mechanically incorporated prior to planting. It has a 48 hour reentry interval following application. RoNeet controls problematic weeds such as malva, purslane, lambsquarters and pigweed.
Dual Magnum provides control of weeds such as burning nettle. One difficulty with the use of this material is that it has a 50 day preharvest interval (PHI). This PHI often necessitates making applications prior to planting clipped spinach which matures in 25-35 days during the summer production season.
Over the past three years we have evaluated Spin-Aid for use in clipped spinach. Spin-Aid is registered for use on processing spinach and has a 21 day preharvest interval (PHI); this use pattern fits the production practices for freezer spinach. However, washing and bagging spinach is also considered processing and would allow its use for clipped spinach. During the summer months, clipped spinach matures in 25-30 days which makes complying with the 21 day preharvest interval difficult. The first opportunity to apply Spin-Aid typically occurs following the germination water at about 8-10 days after planting which makes complying with the 21-day PHI difficult in many situations. Spin-Aid has various warnings on the label regarding phytotoxicity or potential delay of development under some conditions; this is a concern for a rapidly developing crop like clipped spinach. Research conducted a number of years ago indicated that phytotoxicity by phenmedipham was made worse under warm temperatures. As a result, the label stipulates that temperatures >75 °F can cause crop injury. Research carried out by Ran Lati indicated that high light conditions reduced the tolerance of phenmedipham more than temperature in the coastal production district. Given this observation we evaluated the impact of nighttime vs daytime applications of low rates of Spin-Aid (0.5, 1.0 and 2.0 pints/A) for use on clipped spinach.
Research consisted of making morning (high light) and evening (low light) applications of Spin-Aid nine days after seeding when the 1st true leaves were <1/4 inch in size. We observed less phytotoxicity from evening than morning applications (Table 1). Damage to spinach was most significant in morning applications of 2 pint/A Spin-Aid and consisted of necrosis on the tips of some cotyledons (Photo 1); these symptoms were not seen in the 2.0 pint/A evening applications (Photo 2). The 0.5 and 1.0 pint/A rates had acceptable levels of phytotoxicity regardless of application timing. Spin-Aid did not significantly reduce the number of malva plants but stunted them (Photo 3) making them less problematic during harvest as is the case of untreated malva (Photo 4). Nettleleaf goosefoot was susceptible to Spin-Aid and all rates significantly reduced the population of this weed. Commercial-scale trials were carried out in fields that had high populations of weeds. At one site Spin-Aid reduced the number of purslane, shepherd's purse and hairy nightshade by half (Table 2). The overall yield of the standard treatment was 11.007 tons/A and the 1.0 pint/A Spin-Aid treatment was 10.061 tons/A indicating that there may be some yield reduction with the use of Spin-Aid.
The results from these and other trials look promising, but modifications to the current label will be necessary and we are currently working with the manufacturer, Engage Agro, to see if that will be possible. If successful, this will provide a powerful tool to reduce weed pressure in fresh market spinach fields.
Sample costs to produce and harvest romaine hearts and organic spinach in the Central Coast Region – Monterey, Santa Cruz and San Benito counties – are presented in these studies.
The analysis is based upon a hypothetical farm operation of a well-managed farm, using practices common to the region. Input and reviews were provided by growers, UC ANR Cooperative Extension farm advisors and other agricultural associates. Assumptions used to identify current costs for these crops, material inputs, cash and non-cash overhead are described. 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.
These two studies can be downloaded for free from the UC Davis Department of Agriculture and Resource Economics website at http://coststudies.ucdavis.edu. Cost-of-production studies for many commodities are also available.
For additional information or an explanation of the calculations used in the studies, contact Don Stewart at the UC ANR Agricultural Issues Center at (530) 752-4651 or destewart@ucdavis.edu.