Mar 23, 2022Insecticide Modes of Action and IRMTo contact John Palumbo go to: jpalumbo@ag.Arizona.edu
Throughout the desert Southwest and across the nation, we have continued to experience high prices for fertilizers used in crop production agriculture. Accordingly, there are a lot of concerns and many anecdotes being passed around in an effort to understand the causes. Following a review of the current situation, the conditions that have created these high fertilizer prices, and the prospects for the future; there are many factors involved.
What we are experiencing is illustrated nicely in Figure 1, which describes the pattern of anhydrous ammonia (NH3) costs since September 2008. A very similar story is told in review of the costs for urea (46-0-0), diammonium phosphate (DAP, 18-46-0), and most other fertilizer materials. The high price trends we are now seeing began in September 2020.
Fertilizer prices also experienced a rapid increase in 2008 when nitrogen (N) fertilizer prices increased 32%, phosphate 93%, and potash 100%. Prices then dropped to pre-2007 levels by the end of 2009 and in review the surge was primarily due to high global and national demand and low inventories. The conditions we are now experiencing differ from the 2008 situation.
To better understand this current rise in fertilizer prices it is important to recognize that fertilizer is a global commodity and 44% of all fertilizer materials are exported to a different country. Thus, fertilizer production and prices are affected by other countries demanding fertilizer and the transportation rates to get the fertilizer to the final destination are all important factors.
The U.S. is the third-largest producer of fertilizers globally, and we require the importation of N, phosphorus (P), and potassium (K) to fully meet domestic demand. The U.S. fertilizer dealers and producers pay the price defined by the global market and that include the costs for the base fertilizer, other fertilizer materials, and the transportation requirements.
Anhydrous ammonia (NH3) provides a good example of the U.S. production in relation to the rest of the world. In 2020 NH3 was produced at 36 domestic plants and shipped around the country by pipeline, rail, barge, and truck. As of 2018, U.S. ranked second with 11.6% of global in NH3 production. China at 24.6% led in global NH3 production and India was ranked third with 11.3%.
For phosphate fertilizer production, the U.S. ranked 2nd with 9.9% of global production, led by China at 37.7%, and India with 9.8%.
For the mining and processing of potash (K2O) deposits, Canada is the global leader with 31.9% of global production, followed by Belarus with 16.5%, and Russia with 16.1%. The U.S. produces 0.8% of global potash and ranks 11th in the production of the global supply
Thus, the U.S. is not the sole or dominant player in the global fertilizer industry or market. In point of fact, the U.S. share in terms of global use has dropped from 25% in 1961 to 10% in 2018.
Another major factor to consider are the energy requirements for the production and transport of fertilizer materials. Fertilizer production facilities require a large amount of energy to convert the raw chemical materials into their applicable farm-use state. This is very important in terms of N fertilizers.
There are two basic methods of fixing atmospheric diatomic N gas (N2), which is biologically inert and represents 78% of the earth’s atmosphere. The first, is the natural and miraculous process of biological N fixation which converts inert N2gas from the atmosphere into ammonium-N (NH4). The second is the industrial process, which is also amazing, where anhydrous ammonia is produced by the Haber-Bosch process and atmospheric N2 is combined with hydrogen (H) to synthesize the ammonia (NH3). This reaction is not thermodynamically favorable under natural conditions and huge amounts of energy with high temperatures and pressure are required to accomplish the process. In the Haber-Bosch process, natural gas is the H source and it also the energy source for further N fertilizer synthesis.
Energy costs account for 70% to 90% of the fertilizer production variable costs in the synthesis process. For example, 33 million metric British thermal units (MMBtu) per material ton of NH3 are required to make the conversion in the Haber-Bosch process. Natural gas prices have risen dramatically over the past year, especially in Europe where more than a 300% increase has been experienced since March 2021. This has forced many European Union N plants to close.
The aforementioned factors are dominating the increase in fertilizer prices that we are now experiencing. There are also other important factors including supply chain disruptions, trade duties, and geopolitics. These latter factors tend to get a lot of attention in the agricultural communities and the media often exacerbates that impression. But we see from this basic review, that there are many factors at play, and we can also better understand why fertilizer prices are not likely to come down soon.
Myers, S. and N. Nigh. 2021. Too Many to Count: Factors Driving Fertilizer Prices Higher and Higher. Farm Bureau. https://www.fb.org/market-intel/too-many-to-count-factors-driving-fertilizer-prices-higher-and-higher
Figure 1. Pattern of anhydrous ammonia (NH3) costs since September 2008.
Figure 2. Pattern of U.S. share in the global nutrient market since 1961.
DISEASE: Center Rot of Onion
PATHOGEN: Pantoea ananatis, Pantoea agglomerans, Pantoea alli and Pantoea stewartii subsp. indologenes
HOSTS: Onion (Allium cepa L.), garlic (Allium sativum L.), shallots (Allium cepa var. aggregatum L.), leeks (Allium ampeloprasum L.), chives (Allium schoenoprasum L.).
Symptoms and signs
Center rot of onion has not been a major problem in the desert southwest but when the environment is favorable, the disease can cause up to 90% loss. Foliar symptoms (symptoms on leaves) may start with water-soaked lesions spanning the length of the leaf blade, which gradually become blighted resulting in desiccation and collapse of the tissue. Experiments have shown that the bacteria can move from leaves to the bulbs, thus protecting foliage is important to manage the disease.
The bacteria can overseason to infect onions in a number of different ways. Like many bacterial pathogens, P. ananatis can be seed-borne with infested seed serving as a survival mechanism as well as a means of dissemination. It has been demonstrated that P. ananatis can be both naturally seed-borne and seed-transmitted in onion. The significance of the bacterium's ability to colonize seed is uncertain, as most onion seed production sites are located in arid climates but extremely important to understand to manage the disease.
Although P. ananatis can be seedborne, the proposed primary mode of transmission is by two insect vectors. Two species of thrips, tobacco thrips (Frankliniella fusca (Hinds)) and onion thrips (Thrips tabaci), have the ability to transiently acquire and transmit P. ananatis and P. agglomerans . The bacterium can persist in a non-circulative manner in the gut of thrips for 128 h, allowing the vector to infect plants over an extended period of time.
P. ananatis can survive epiphytically and endophytically on a wide range of hosts. These alternative hosts can serve as a source of inoculum in fields where susceptible crops are grown. In Georgia alone, 25 weed species, including carpetweed (Mollugo verticillata), common ragweed (Ambrosia artemisiifolia), crabgrass (Digitaria sanguinalis), common cocklebur (Xanthium pensylvanicum), curly dock (Rumex crispus), Florida pusley (Richardia scabra), sicklepod (Cassia obtusifolia), stinkweed (Thlaspi arvense), Texas panicum (Panicum texanum), vaseygrass (Paspalum urvillei), wild radish (Brassica spp.), yellow nutsedge (Cyperus esculentus) and other multiple crop plants were found to harbor P. ananatis populations asymptomatically.
Pic Credit: Colton Tew
Onion cultivars resistant to Pantoea sp. are not commercially available. Use of certified onion seeds is encouraged to avoid introduction of Pantoea sp. inoculum in the production field. Planting early maturing or mid-maturing onion varieties are often recommended for growers. Late maturing varieties provide a larger window for infection and a potential epidemic to occur, which are favored by thrips pressure, hot and humid conditions, and lack of effective bactericides. Overhead irrigation should be avoided as it promotes bacterial spread compared with sub-surface or drip-irrigation. Controlling thrips population can be an effective management strategy to reduce center rot incidence as these vectors play an important role in bacterial transmission.
Center rot management in onion fields relies heavily on copper applications mixed with an ethylenebisdithiocarbamate fungicide (EBDC), such as mancozeb, which growers may apply weekly as a protectant. In addition, researchers found P. ananatis strains to be copper-tolerant indicating overuse and potential risk of insensitivity to this chemistry. Repeated applications of copper sprays during susceptible growth stages can be effective only to a limited extent and does not offer a robust solution to the problem. Perhaps the inefficacy of these sprays could be due to thrips preference to colonize certain parts of the onion plant, e.g. the basal meristems (neck region).
The implementation of successful weed management strategies are important in reducing P. ananatis inoculum in the field. By reducing weeds, growers can potentially reduce initial inoculum.
Vol. 13, Issue 3, Published 2/9/2022
Over the last couple of years, we have been investigated the use of band-steam to control weeds and soilborne pathogens. The technique has been discussed in previous UA Veg IPM articles (Vol. 12 (5), Vol. 11 (15). Briefly, the concept behind band-steam is to disinfest narrow bands of soil centered on the seedline using high temperature steam prior to planting.
Trials results have been impressive, particularly for in-row weed control (Fig. 1). We’ll be demonstrating our prototype band-steam applicator (Fig. 2) and sharing study results at the 2022 Southwest Ag Summit Field Demo, February 23rd. More information about the event can be found at: https://yumafreshveg.com/southwest-ag-summit/. I look forward to seeing everyone there.
If you are interested in trying band-steam on your farm, please let me know. We are in the process of constructing a second-generation band-steam applicator that has a higher capacity steam generator and simpler design than our first prototype and are seeking collaborators.
This work is partially funded by the Arizona Specialty Crop Block Grant Program.
Fig. 1. Weed control in seedline of beds treated with band-steam (center and left bed) and untreated (right).
Fig. 2. Band-steaming bed seedlines prior to planting in preparation for the 2022 Southwest Ag Summit Field Demo, February 23rd (https://yumafreshveg.com/southwest-ag-summit/).
Pigweeds are some of the most common summer annual broadleaf weeds in the low deserts. Although they are often lumped together, there are 4 different species of pigweed that are common here and more than 10 species that occur as weeds in California and Arizona. Their growth habits and response to herbicides are similar. It is easy to identify them by physical characteristics but one species of pigweed can hybridize with another and become less distinguishable.
Palmer Amaranth (Amaranthus palmeri) is probably the most common pigweed species found in this region. It is very aggressive and fast growing and can become 6 feet tall or higher if uncontrolled. It has one thick stem and several lateral branches. The leaves are lance shaped, hairless and have distinctive white veins on the underside. It has flowering tassels that become stiff and spiny. This species has become resistant to Glyphosate in many parts of the county.
Redroot Pigweed (Amaranthus retroflexus) is probably the second most common pigweed species. It is shorter and the seed heads are smaller, in clusters and have stiff spine-like scales. It has leaf hairs on the margins and the veins are often reddish. The lower stems are often reddish. This species will hybridize with Palmer Amaranth and become less distinguishable.
Tumble Pigweed (Amaranthus albus) is very different from Palmers or Redroot. It grows lower to the ground and has many branches that turn upright. The leaves are much smaller and narrower. The numerous stems are light green rather than red. The seed heads are small, spiny and at the base of the leaves rather than in long terminal spikes. When mature, the branches are sticky, stiff bristles that break off at the ground and tumble with the wind.
Prostrate Pigweed (Amaranthus blitoides) is very similar to Tumble Pigweed but the stems are more prostrate, grow close to the ground and form mats. The stems and leaves are smaller and reddish rather than light green.
Results of pheromone and sticky trap catches can be viewed HERE.
Results of pheromone and sticky trap catches can be viewed HERE.
Corn earworm: CEW moth activity increased a bit in the past 2 weeks but remains well below average for late spring.
Beet armyworm: Moth counts increased slightly, but remain very low consistent with seasonal temperatures, and below average for this point in the season.
Cabbage looper: Significant increase in activity in Dome Valley, Gila Valley and Tacna, but moth counts remain unusually low for this time of year, as they have all season.
Whitefly: No adult movement recorded across all locations and overall low numbers consistent with temperatures.
Thrips: Thrips adult movement beginning to pick up considerably, particularly in Yuma and Dome Valleys. Movement is below average for late March.
Aphids: Seasonal aphid counts down considerably compared with the Feb and Jan. Counts highest in Bard and Gila Valley. Below average movement for this time of year. Majority of species found on traps were green peach aphid.
Leafminers: Adult activity up slightly in some locations, but well below average for late season.