In our community garden plots alot of carrots are misshapen. Our tomato plants also had brown leaves and branches after first fruit although some new growth with tomato came back.
There are number of reasons that carrots can become misshapen, including spacing, soil issues, nutrient issues and diseases or pests. If carrots are intertwined, they have likely been grown too close together. To avoid this issue, thin plants out to at least an inch apart after the stalks are around three inches high to allow for adequate space for the maturing roots. If the carrots are stunted or growing split roots, the problem may be soil that has too many rocks, hard clay lumps or may be too compact. Carrots prefer loose, slightly sandy soil. Next year make sure to work the soil only after it is dry, and to remove rocks and break up large lumps. You can also amend the soil with organic matter to improve its texture. Multiple small root branches and hairs may be caused by too much nitrogen. Fertilizing with fresh manure or adding nitrogen rich fertilizers immediately before planting will increase the nitrogen levels in the soil. Consider applying fresh manure in the late fall, or use well composted manure in the spring. You may also want to rotate your plantings with another crop that thrives on higher nitrogen levels, such as broccoli, corn or lettuce. Nematodes are microscopic worms that can cause carrots to become pitted, stunted or produce lesions. It is impossible to identify whether your soil is infected with nematodes without a laboratory test. Rotating the site with crops from different families (e.g. non-root crops) at least every three years is a good practice to manage pests and maintain soil conditions.
There are a number of environmental conditions, pests and plant diseases that can cause tomato leaves to brown. For those of us that live in Ontario, our wet, cool spring has provided the perfect conditions for a number of fungal diseases which can cause browning of both leaves and stems. It is important to clear the area of all foliage in the fall to reduce the further spread of fungal spore than can overwinter in leave debris. Again, rotating your crops every three years with crops from a different family is a good practice to control a variety of diseases and pests.
Below are some links to couple of other references that you might find helpful with this issue:
Savvy Gardening: Planting & Thinning Carrots
Nematode Control in the Home Vegetable Garden
Missouri Botanical Garden:/Tomato Foliage Problems