PBS News recently did a story on the importance of Yuma’s winter vegetable production and the pressures the Western US is facing due to water scarcity. The story features insights from local growers Matt McGuire, JV Smith Companies and Jon Dinsmore, Dinsmore Farms, as well as Arizona Department of Agriculture Director, Paul Brierley. The report is well done, covering the basics of Yuma agriculture and the water shortage issues the industry is facing. It’s a quality piece, worth a listen.
Check it out by clicking here or on the image below.
Fig. 1. PBS NewsHour: “Arizona Farmers Forced to Adapt as Main Water Source Dries Up” story. (Photo Credits: PBS News)
Calvin’s lab conducted an experiment this fall to evaluate bioinsecticides that can help to control pale striped flea beetles inorganic crops. The experiment was conducted at the Yuma Agricultural Center experimental farm. Four insecticides and insecticide mixes, including Biolink (insect& bird repellent), Biolink + Pyganic, Pyganic, and M-Pede + Entrust, were evaluated along with a nontreated check. Insecticide treatments were applied using chemigation through sprinklers during the last 40 minutes of germination water. Each treatment was applied to a strip of 10 beds of cabbage, and each strip was divided into 4 subsections representing 4 replications. Precautions were taken to avoid cross-contamination across treatments. Because there was a stand issue, stand count data was not considered for evaluation. The treatments were compared using the percentage of damaged plant data. This data was collected by inspecting 20 plants per subsection. We also inspected each of these 20 plants and their immediate surroundings for the presence of flea beetle adults. While we observed a lot of flea beetle damage, we only saw one flea beetle throughout the experiment. The assessment was made on the 4thand the 7th day after application (DAA).
At 4 DAA, all insecticide-treated strips showed a comparable reduction in injured plants. However, only Biolink, Biolink +Pyganic, and M-Pede + Entrust exhibited a level of injured plants that was significantly lower than that of the non-treated control. At 7 DAA, only Biolink showed injured plant incidence that was significantly lower than that of the non-treated control. However, Biolink + Pyganic, and M-Pede + Entrust were comparable to the Biolink alone treatment (Figure 1). The data suggests that the evaluated bioinsecticides and bioinsecticide mixes can be used alternatively when targeting pale striped flea beetles in brassica seedlings. However, an additional application after 4 DAA would be necessary for better protection of the crop.
Figure 1a. Brassica plant with flea beetle feeding injury
Figure 1b. Adult pale striped flea beetle.
Figure 2. Means percentage of cabbage plants damaged by flea beetles. Bars
with the same capital letter or lowercase letter are not statistically different. IBR
= Biolink (insect & bird repellent).
Both organic and conventional lettuce are high-demand crops for nitrogen, with organic lettuce requiring organic nitrogen and conventional lettuce requiring general nitrogen sources. Lettuce requires a substantial amount of nitrogen to support its growth, particularly during the heading stage when most nitrogen uptake occurs. This demand is driven by its rapid growth rate and the production of large leaf biomass.
Organic nitrogen/nitrogen management for lettuce production in Yuma, Arizona, is acritical aspect of efficient and sustainable agriculture. Proper nutrition(organic nitrogen or nitrogen) management can improve crop yield, reduce environmental impact, and optimize resource use. This is significantly correlated with sufficient soil moisture availability. As a result, improper or excessive water and nutrient management for both organic and conventional lettuce production systems could significantly and negatively impact growth, development, and yield quality.
Moreover, several studies have reported that proper water and nitrogen management could potentially reduce aphid attraction to lettuce, as aphids are more prevalent in lettuce with higher nitrogen content. Elevated nitrogen levels in lettuce can attract and support larger aphid populations.
There are many approaches that could be adopted for coupled water and nutrient management, or in other words, best management practices to avoid excessive or inadequate application of either element. After soil sample analysis in the pre-season, one of these approaches involves utilizing high-tech site-specific sensors, which can be installed between two healthy plants that represent the majority of the field to monitor nitrate-N levels in the soil throughout the growing season. These sensors monitor nitrate-N levels on a daily or weekly basis to evaluate nutrient levels at different soil profile depths, especially during critical lettuce growth stages. Many studies have reported that site-specific, sensor-based nutrient management increases efficiency compared to traditional methods, resulting in significant nitrogen savings.
Preliminary results from ongoing research comparing nutrient levels by utilizing AquaSpy Nitrate sensor (Figures 1. 2. And 3) with soil analysis conducted in the lab (Ward Laboratories Inc.) as part of the study on organic vs. conventional iceberg lettuce under subsurface drip irrigation at the Yuma Ag Center-Valley Research Center, suggest that the findings are comparable to a considerable extent so far. Soil moisture availability and soil temperature fluctuations significantly influence the data reflected by the sensors, particularly at varying profile depths. This is an ongoing project; however, the results are promising regarding the aforementioned objectives in organic and conventional lettuce production systems. Stay tuned for the results and conclusions after harvesting.
Figure 1. Nitrate sensor from AquaSpy was installed between two healthy plants in the
organic lettuce production field at the Valley Research Center at the University of
Arizona, Yuma Agricultural Center, Yuma, Arizona.
Figure 2. Nitrate level in the conventional lettuce production field at the Valley Research
Center at the University of Arizona, Yuma Agricultural Center, Yuma, Arizona.
