If it is a sqarrosa type, like Boulevard, Squarrosa Lutea, Veitchi, etc., then it's probably just normal if the tree is 4 ft or larger. One of the unattractive qualities of this type of false cypress as they age. Of course, any undesireable environmental problems like those previously mentioned will increase the problem. Do you know the name?

do NOT increase water.. until you dig a hole and find out if it is wet or dry ... the black fabric is cooking your plants above ground... and probably cooking the roots below with trapped and retained heat ... i doubt if you will find any experienced gardener.. who favors any kind of landscape cloth ... interior browning is normal.. there is no sunlight in there.. to maintain green leaves... its a function of how tight the outer canopy is .. the all brown plant is dead ... why did you not finish covering the black with the stone ... no one can tell you about your soil.. you water.. when your plants .. needs water.. run irrigation.. dig hole.. find out what happened.. increase or decease amount of time run.. as necessary ... ken

Assuming they are getting near full sun (they demand a lot), then I am going to say it's an over watering issue. You don't say how many gallons you are providing per watering session, but anything over 1x per week this summer seems excessive for Leyland. I know it's been dry, but generally cool summer on the East Coast... and Leyland is about the most drought tolerant conifer I have planted. Mine have been in the ground 3 years now, so now supplemental water was provided for them at all this year, but even in year 1, I recall going very light on the water and they did excellent. I would say 3 gallons 1x per week in stretches without rain would probably be more than enough for Leylands, but you need to check the soil for moisture.

Please, don't suggest that she commit illegal acts. Besides, it won't work that well anyway. Lets see. The vindictive old guy suddenly sees all of his trees die off, maybe the grass around them too. He knows that the only person who would profit from it is this neighbor who has been feuding about those trees for the last couple of years. So the next act of vindictive old guy is to put in an ugly metal privacy fence 10 feet high. Or perhaps he decides this is the spot to establish that junkyard he has always wanted to find a spot for. So a pile of rusted tractors and farm implements suddenly appear in that corner of his property, and maybe a junked car or two. He might even replant those trees on his side of the junk, so he does not need to look at it. Even if nobody can prove that you did it, the vindictive, pissed off old guy knows who did it. Doing something stupid will only escalate the fight. John