**1. Introduction**

Corn, also referred to as Maize, *Zea mays*, is an annual grass in the family Poaceae and is the third most widely grown cereal after wheat and rice throughout the world [1]. It is a staple food crop which has a total production of 1.09 billion metric tons achieved in 2018/2019, [2] and still a vital source of energy and protein in humans' diet and animals, hence ensuring food security globally [3]. The United States was recorded to be the largest corn producer in the world with an estimated volume of 345 million metric tons in 2019/20 which is approximately one third of corn produced globally. In that year, China and Brazil were the next top corn producing countries after the United States [4].

The origin of corn is quite unknown but history revealed that corn was first domesticated in Mexico's Tehuacan Valley. There are several types of corn which include sweet corn, popcorn, pod corn, flint corn, flour corn, waxy corn and dent corn. In the United States corn is known to be an important crop and in the past few years, the country's corn farmers experienced constant increases in annual revenues [4].

However, during preharvest and postharvest operations, insect pests and microorganisms attack maize, thereby reducing both the qualitative and quantitative value of maize [5]. In addition to the reduction of production yield, some pathogens produce toxins that are detrimental to both man and animals' health, they also reduce the nutritive value of maize and thus negatively impacting world food security [6]. A vast number of pathogenic microorganisms (fungi, bacteria, virus) and insects damage maize grains and plant; leading to worldwide annual losses of 9.4%. Insects are known to the the most important cause of deterioration and low yield of maize followed by fungi [7, 8]. Maize pests happens to be one of the major challenges of growing maize and some of the major threat to maize mainly include insect pests (stalk borers and armyworms) and soil pests (wireworms and rootworms). The damaged caused by the western corn rootworm (*Diabrotica virgifera virgifera*) in Europe and in USA is estimated to be more than \$1 billion annually [9]. Roberts et al. [10] also reported the annual losses attributed to plant diseases to be about 40 billion dollars worldwide either directly or indirectly.

There are three significant and most noxious soil-borne pathogens that infest maize in the field namely; *Fusarium* species, *Rhizoctonia* spp. and *Verticillium* spp. [11, 12]. Furthermore, three fungal pathogens that are mostly found in stored grains are *Aspergillus* spp., *Penicillium* spp., *Fusarium* spp. [13, 14] and some xerophytic species, a number of them are known to produce toxins that causes adverse health problems including death [14–16]. The control of these microorganisms are difficult to quell due to their ability to utilize various infection modes to overcome maize immune system, possession of important structures for pathogenesis that are resistance to adverse conditions and the development of some resistance genes that ae understudied [17]. Over the years, pests and diseases management have depended majorly on the use of pesticides and agricultural practices such as crop rotation and irrigation for control of pests and diseases [18, 19]. However, the potency and environmental concerns such as its possibility of destroying beneficial microorganism and insects that promote plant growth and health, bioaccumulation of the chemicals on crops and their harvest, as well as pathogen resistance to some pesticides, have encouraged the pursuit for an alternative that is ecofriendly, less expensive, more sustainable in the management of pests and diseases [20, 21]. Amidst these alternatives, biological control method seems to be the preferable and acceptable option. Biological control using microorganism is an important tool for controlling and managing plant pests and diseases in sustainable agriculture [22].

Microbial biological control agents (MBCAs) are applied to crops for biological control of plant pathogens, they use various modes of action. Their mode of action may include nutrient competition, antagonist relationship (hyperparasitism and antibiosis) against the pathogen or by inducing resistance or priming plants without any direct interaction with the targeted pathogen [23]. In addition to using microorganism as biocontrol of pathogens, microorganisms known as entomopathogens are used in the control arthropods such as insects, mites, and ticks that infest and deteriorate maize. Diverse species of bacteria, fungi, nematodes, and viruses are used in pest management. The use of entomopathogens as biopesticides in pest management is referred to as microbial control, which can be an integral part of integrated pest management (IPM) [24].

In rhizosphere of plants, microorganisms do interact and display different associations, some may be mutualistic, commensal or even pathogenic [25–27]. Interestingly, maize' rhizosphere contains some specific microorganisms that are beneficial to its growth [28, 29]. Positive interactions in rhizospheres are known to be of importance all through the plant's life-cycle [30]. In recent years, there have been an increased interest on the issue of inoculating rhizobacteria into

*Microbiological Control: A New Age of Maize Production DOI: http://dx.doi.org/10.5772/intechopen.97464*

the agricultural soil because they are known to increase productivity and quality of agriculturally important crops and help to the stabilize agroecosystems [31]. Inoculation of maize with various plant growth-promoting rhizobacteria (PGPR) strains, however could result in significant increases in plant biomass, root and shoot length and uptake of essential plant nutrients. The use of plant growth-promoting rhizobacteria (PGPR) is a promising alternative method to external chemical inputs to improve crop yield in sustainable agricultural systems [32]. PGPR's modes of action include nutrient uptake, stress protection, induced resistance and plant growth promotion by production of phytohormones [33–35].

With respect to the severe maize' annual losses, and threat to food security caused by pathogens and insect pests, thus the need for Microbiological control methods to minimize losses caused by pathogens and insect pests. This scope of this chapter concentrates on the use of microbiological agents; an alternative, safe, less toxic, and less disruptive method of controlling the growth and development of pathogens and insect pests of maize, and optimizing maize production.
