Miller Magazine Issue 110 / February 2019

Nitrogen can also be easily generated using molecular membrane generators. These are capable of purging vertical grain storages of 120 tons capacity within 3 hours (Timlick et al. 2002). By maintaining a slight positive bin pressure, concentrations within a sealed commercial storage could be maintained (compensation for leakage) and insect mortality was significant after 14 days at 17ºC. In terms of efficacy and efficiency, there is not much diffe- rence between using CO ₂ over traditional fumigants such as phosphine. Nitrogen has been considered unsuitable for bulk commodity treatment at export position because the length of time required for significant mortality of the pests in ques- tion is too long. However, effective management procedures can allow for N ₂ use when temperatures are appropriate. All require effective sealing and monitoring and efficiency is di- rectly correlated to temperature. While caution is necessary when utilizing any product as an atmospheric control, there are no residues of concern when utilizing MA. Aeration after treatment is of less concern, thereby allowing for outturn of product in export position minimizing concerns for worker safety. Product availability is not an issue. Flexible liners and their associated loading/unloading equipment and nitrogen generators are all available commercially and can be set up and maintained with product replenished on site. Maintenance of sealing of hermetic storage has proven a challenge at times. Large bunkers and grain bags in Australia often have sealing breached by birds pecking holes in the liner. In Canada, deer often break the seals of hermetically stored grain in bags. Consequently, some focused research on liner integrity may be of use in these types of situations. Discovery of breached seals during CA treatments can be difficult to remedy, underlining the necessity of performing pressure testing before application. RECENT DEVELOPMENTS A significant aspect of MA/CA treatment is our ability to monitor the gas concentrations in the gastight structu- res. Similar to fumigation, O ₂ and/or CO ₂ concentrations should be monitored to ensure a successful application. As a common practice gas sampling lines have been installed for monitoring using gas measurement instruments. Such monitoring is performed by technical personnel on site at predetermined regular times, particularly during gas pur- ging and during the exposure time to MA/CA treatment. The conventional method of such monitoring is the visit of the technical personnel on regular basis to monitor the changes in gas concentrations. This method necessitates precious time and travel of the technical personnel, which makes the monitoring expensive. Wireless sensors for monitoring O ₂ and/or CO ₂ concent- rations, relative humidity and temperature have been de- veloped to enable the technical personnel record the data (Centaur Analytics, 2018). Such development facilitates the analysis of the MA/CA treated enclosures without the pre- sence of the technical personnel on site. Since the exposure time of MA/CA treatments last many days and the treated structures may be located at distant sites then the location of the operator, such development offers an excellent tool that can be incorporated to the package of the MA/CA tre- atments. Such wireless monitoring assists the operator in decision making on the necessity of intervention during the treatment. References Adler, C., H.G. Corinth, and C. Reichmuth. 2000. Modified atmospheres. In Bh. Subramanyam and D.W. Hagstrum (Eds.). Ch. 5, pp. 105-146. Alternatives to pesticides in stored-product IPM. Kluwer Academic Publishing, Norwell, MA. Alagusundaram, K., D.S. Jayas, N.D.G. White, W.E. Muir and R.N. Sinha. 1995. Controlling Cryptolestes ferrugineus (Stephens) adults in wheat stored in bol- ted-metal bins using elevated carbon dioxide. Canadian Agricultural Engineering 37: 217-223. Annis, P.C. 1987. Towards rational controlled atmosphere dosage schedules: a review of current knowledge. pp. 128-148. Donahaye, E. and S. Navarro (eds.). Proceedings of the 4th International Working Conference on Stored Product Pro- tection. Tel Aviv, Israel. Banks, H.J. and P.C. Annis. 1990. Comparative advantages of high CO2 or low O2 types of controlled atmospheres for grain storage. pp. 93-122. In: Calderon, M. and R. Barkai Golan (eds.). Food Preservation by Modified Atmospheres. CRC Press, Boca Raton, FL. Bond, E. J. 1984. Manual of fumigation for insect control. FAO Plant Production and Protection Paper No. 54, 432 p. Calderon, M. and R. Barkai Golan. 1990. Food Preservation by Modified At- mospheres. CRC Press, Boca Raton, FL. Cassels, J., Banks, J. and Allanson, R. 2000. Applications of pressure swing ab- sorption (PSA) and liquid nitrogen as methods for providing controlled atmosphe- res in grain terminals. In: Proc 6th Int Work Conf Stored-Product Protection pp. 57-63. Centaur Analytics (2018) https://centaur.ag/ (last visited February 2019) Clamp, P. and Moore, D. 2000. Nitrogen treatment of grain, Newcastle Grain Terminal. Australian Postharvest Technical Conference, 184-186. Mann, D., Jayas, D., Muir, W., White, N., 1997. Conducting a Successful CO2 Fumigation in a welded-steel hopper bin. Proc ASAE, ASAE paper no. 976064. Minneapolis, MN, Aug. 1997 Moylan Silos. 2011. Moylangrainsilos.com/moylanproducts.htm. 09/02/2011. Navarro, S. 2006. Modified Atmospheres for the Control of Stored Product Insects and Mites. Chapter 11 in: Insect Management for Food Storage and Pro- cessing. Second Edition. J.W. Heaps ed. AACC International, St. Paul USA. Nicolas, G. and D. Sillans. 1989. Immediate and latent effects of carbon dioxi- de on insects. Annual Review of Entomology 34: 97-116. Sigaut, F. 1988. A method for identifying grain storage techniques and its app- lication for European agricultural history. Tools and Tillage VI: 3-32. Timlick, B., Dickie, G. and McKinnon, D., 2002. Nitrogen as a major compo- nent of a controlled atmosphere to manage stored product insect pests in large vertical storage. In: Intergrated protection of stored products, IOBC Bulletin 25(3) 193-197. White N. and Jayas D., 1991. Control of Insects and Mites with carbon dioxide in wheat stored at cool temperatures in non-airtight bins. Journal of Economic Entomology 86: 1933-1942. Williams, P., Minett, W., Navarro, S. and Amos, T.G. 1980. Sealing a farm silo for insect control by nitrogen swamping for fumigation. Aust. J. Exp. Anim. Husb. 20: 108-114. Figure 3: Online platform for monitoring storage conditions and fumigation treatment real time and prevent spoilage (centaur.ag ).