One of the more difficult aspects of developing or managing a vineyard is determining who to hire for specialized expertise. The following approach is recommended.
Identify the general realm of the problem. If you want an appraisal of a land's suitability for winegrape production, find a soil scientist. Many viticulturists will present themselves as capable soil scientists, but are not. They have neither the in-depth training nor the expertise in soil physical and chemical properties and behavior to competently evaluate soil. If the problem is pests or disease, call upon a certified Pest Control Advisor (PCA). Pest Control Advisors are certified by the state of California after passing written tests in specialty subjects (Insects & Mites, Diseases, Nematodes, etc.). In addition they are required to earn continuing education credit hours each year to keep them up to date in the technologies available and to maintain their license.
Identify several potential consultants to help with problem diagnosis and treatments. Ask colleagues in the industry who they know about. Call the local county viticultural agent for recommendations. Call on viticulture faculty at local community colleges and universities. They frequently ask consultants to give guest lectures to bring a "real world" flavor to their students. Google key terms or candidate names to find out who is out there and if they are mentioned in the press. In addition to their own website, are the candidates mentioned in other web-sites? Are they frequently asked to give talks to growers groups? Invited speakers are usually very well respected in their field in order to get the invitation from the committee that invited them.
Check the qualifications of your candidates. Many consultants over-reach their areas of expertise to secure the job. If the problem is soil, then make sure the consultant is a soil scientist with university degrees. Many agronomists or viticulturists will masquerade as a soil scientist because they had 1 or 2 classes in soil science during their degree program. A soil scientist with a MS or Ph.D. will probably have had 15 to 20 classes in all of the major and most minor sub-disciplines of soil science including soil fertility, soil chemistry, soil physics, soil microbiology, soil genesis, soil morphology, soil mineralogy. Soil scientists with post graduate degrees will frequently have had both the undergraduate, as well as the more in-depth graduate course of the same title. Some poorly qualified consultants will emphasize their many years of experience to over-ride their weak formal training in their field. Do not be fooled, experience without formal training, just means they may have been missing the same symptoms for all of those years because they did not know all of the characteristics of the soil-plant interface of which they should have been aware. The soil science degree curriculum is one of the most chemistry intensive disciplines in the agricultural sciences. Therefore a soil scientist is more likely to understand the impact of a treatment for one soil chemistry imbalance on other soil properties, thereby lessening the chance of creating another soil chemistry problem, from the treatment of original.
Speak with candidates on the phone to ask questions about their experience and ask for names and phone numbers of their clients you can call for references. Consultants are not cheap, so time checking their histories and success with other clients is time well spent. Explain your impression of the problem and ask the consultant how they will approach a diagnosis. Does the strategy seem reasonable? Are the easiest and least expensive tests conducted before the more expensive? Ask for a proposal with expected expenses. Some consultants will ask to make a field visit prior to providing a strategy or proposal. This should be welcomed. Some will provide that first hour for free, some may charge, but at least it provides you with an interface with the consultant in the field before spending the big bucks.
Make sure the consultant's report addresses the problem and justifies the recommendations. A consultant that cannot diagnose the problem may try to dance around the issue, by making general recommendations about adding more fertilizer to spark more vine growth. If the diagnosis is not justified by the data, be wary. A few consultants out there will not justify their recommendations and profess that their justification is proprietary information. This is hogwash. Essentially all information that justifies the treatment of a disorder is based on published research results that are in the public domain. Yes, your consultant may have put a few pieces of information together to diagnose or treat the problem, but would you undergo surgery just because the doctor said you should, but he wouldn't go over your symptoms and the results of his test to justify why.
Once you get a treatment regime, follow it. Do not mix parts of one consultant's strategies with another's. There are frequently many ways to skin a grape (I am a cat lover), but starting one method and finishing with another may not solve the problem. If the recommended treatments seem unreasonable, ask for justification or a less complex or less expensive alternative. You can also call another consultant to review the first consultant's data and recommendations. This may get expensive, because if your first consultant did a poor job in data collection, the second consultant may need to re-do some of the baseline data before rendering more recommendations.
Spread the word. If you had a good or bad experience with a consultant let your colleagues know. Word of mouth is the best recommendation.