Every cultivator will encounter problems with their grows at some point. Some problems are a simple fix, others can't be fixed at all. The common problem I've seen when a new cultivator asks for my assistance is simple impatience. Patience is mandatory in this hobby as some species require months to fruit properly. I recommend that new cultivators start with Oysters since that is the closes you will get to instant gratification in this hobby. If you think that your grow is behind schedule, compare your time frames to those reported in grow logs posted on the Shroomery or Myco-Tek, more often than not, you'll find that you're getting ahead of yourself. If this is not the case though, and your grow is behind schedule, then it's time to reevaluate your methods and the fruiting environment itself. Go back and read over the guides you used, and double check your species' growth parameters to make sure you are providing an ideal atmosphere for your mushrooms.
COMMON PROBLEMS AND THEIR SOLUTIONS
Problem 1: Contamination
Contamination happens. No matter how perfect your technique is, some day you will run into the mean green (trichoderma, green mold), cobweb mold, black mold, orange ooze, or one of many other contaminate problems. This usually happens during the colonization of spawn jars, but can also happen with bulk substrates if they are not prepared correctly. Most of the time a colonized bulk substrate is the result of an unnoticed contaminate in the spawn jar. Most often you will see contaminates when you slip up on your inoculations, or a liquid culture has been contaminated. Liquid cultures are the first suspect because given enough time, any culture medium will contaminate. The risk of contamination is compounded when multiple inoculations are involved, so since liquid cultures get a lot of needle time, they are at the highest risk. The risks of contamination also increase when there is too much water in the substrate.
Unfortunately, once a substrate is contaminated, it's very rare to be able to save it. Small patches of cobweb mold can be treated with a H2O2/water dilution being sprays on the substrate, but with other contaminates, you're better off tossing the substrate on the compost heap and waiting for nature to provide some saving grace that may or may not arrive. Black mold and bacterial contamination should be destroyed with heat as they can be harmful to human health. Never open a contaminated substrate indoors as a high concentration of contaminate spores will be released into the area and significantly increase the risk of future contamination.
Problem 2: Slow or Stalled Growth
In jars, this is usually caused by restricted gas exchange, inappropriate temperatures, incorrect water content, or contamination. In rare cases, senescence can also be the culprit. Restricted gas exchange is usually caused by keeping the foil on the jars, or leaving them in an enclosed space. In the case of water content, all you can do is wait and see what happens.
In colonized substrates, this is usually cause by a problem with the fruiting environment (fresh air exchange, temperature, humidity), or a lack of water in the substrate. If the environment is checked as correct, dunk the substrate in water to allow it to reabsorb lost moisture. Once the substrate is rehydrated, return it to fruiting conditions. Most substrates should be dunked after each harvest. PF cakes should be dunked for 12 to 24 hours, bulk substrates should be dunked 4 to 12 hours. Make sure you weight the substrate down as it will float.
Problem 3: Oddly Shaped Fruits
Mutants are common with some species and should not be worried about. They are perfectly safe to eat, and in some cases, are desirable as a novelty. However, mutants that are created through abuse, such as directly spraying Lysol on the substrate, should be discarded as this is caused my chemical mutation rather than a genetic one. Mutants can be safely engineered in some species through the use of black lights.
Problem 4: Fuzzy Feet
Caused by a lack of fresh air exchange. Aerial mycelium forms in high CO2 environments, and discourages pinning and fruit development. Some fruits will grow, but better results will be achieved if more fresh air is introduced.
Problem 5: Stressed Substrate, Cracked Caps
Caused by low humidity or dehydration of the substrate. Rehydrate the substrate and provide more humidity.