When I hear about a shrub wilting and it is not lack of water, I always suspect a root problem such as a mole or other underground rodent. When it comes to pines however there are other insects and diseases that can cause yellow needles and die back. Weevils leave tiny drops of resin, scale shows up as small bumps on the branches and the webworm leaves brown frass on the needles. Then there are some blights, rust and fungal infections that can weaken pine trees. If you can send more information and include an image I might be of more help. If you are losing large shrubs you may want to contact a local arborist to help give you a definitive answer by examining the pines in person and checking with a magnifying glass for signs of insect or disease. Now for your second question - I need a description or photo of the weed that is over running your yard. You can control most weeds by hand pulling or by using a mulch or an herbicide. Dig in and get control now before summer heats up. Keep growing, Marianne Binetti