first you should go through all of them, then you have to master one or two algorithms, and start implement them in Enterprise systems and solution in many business fields.
Programming language doesn't matter for now, the most important is to understand the mathematical logic. then you decide which language will be suitable for you to use.
I fully agree with Michael's answer. In addition to these, you should consider image processing techniques, computer vision and machine vision if you are dealing with image and/or pattern related problems as aflatoxin detection by machine vision or leaf or plant recognition systems etc. On the other hand machine learning can also be adopted on agro-related problems where you have time series or sensor data. In this case, it would be better mastering on feature extraction, dimensionality reduction and feature selection schemes along with regression or classification algorithms. To achieve practical yet efficient tool, you can use Matlab. If you are familiar to java programming language, you can use weka and open cezeri library etc. If you have further question do not hesitate ask more questions here or via e-mail.