Don't know how close UCONN ext is to you/her, and what they charge, but state CAES lab has offices in Windsor and the main plant pathology lab in New Haven. They won't charge anything to look at it, you can call to see if pathologist is in the office today and can even get answer on the spot if you bring it in while he/she is there Here is a link that might be useful: CAES Plant Disease page

My stapeliads don't take a lot of water. Absolutely almost none during the winter, about once a month, BUT My stapelieds live in a colder place than Australia during the winter. They are in a an unheated structure that stays above freezing. I find over watering is the bugger. The y will root from the tops very easily. I have had rot at the roots during spring because I started watering too soon and I allowed them to get a tad to cold in the winter. They reroot themselves once the temps have warmed up considerably. This winter I threw towels over them when it got to 40F ( 5C). That period of demise seems to have been less. The most sensitive of my stapeliads was Huernia zebrina, But it will reroot with ease.. During HOT Texas summer , I water once a week. That said, I need to go out and water . I missed my sunday watering because I was working. Below is Marten Heigand's habitat photos. It does look like semi arid zones with summer rainfall. Some look like texas brush country, but I know it is different. This is a great site to wander around. Here is a link that might be useful: Marten Heigand's Habbitat photos

While mature lavender plants can tolerate a limited amount of drought conditions, lavender can really take quite a bit of water, as long as you've provided good drainage. Potted plants will always use much more water than plants in the garden. And a small pot will always dry out much more quickly than a large pot. Potting mixes, when allowed to dry out completely, become water repellent. The solution is to immerse the pot, plant and all, in a bucket or tub of water, leave until the air bubbles cease to rise to the surface, remove. This redydrates the 'soil', enabling the roots to access the moisture once again. I suggest your plants are dying of thirst. 'Tolerates some drought when mature' does NOT mean 'likes desert conditions'.

Sounds like you got the root issue sorted out. I wanted to add another little tip for any one else who might stumble across this thread. PH is a big issue to plant health like the thread creator found out. One big issue to PH swings is the presence of bad bacteria and fungus in high amounts. Odd or bad smells and slime on the walls of the reservoir and on the roots is a sign of this. It is very important to get the natural beneficial bacteria and fungus to colonize before the bad ones. I use General Hydroponic's Subculture B to Inoculate the roots and to get new systems set up on the right track. After the beneficial microbes have taken a firm root in the system the PH will no longer rapidly swing and the smells will go away. During water changes leave a little of the original water in the system to help keep them colonized. If you find your self with bad odors, slime, and root rot add some 3% Hydrogen Peroxide to the system and let it flush for 24 hours then change the water. Let the system run for a couple more days and repeat the process. Do this a few times then flush the system to get rid of the hydrogen peroxide residues that might be present. Then mix up a new water batch with out the hydrogen peroxide and add some Subculture B. Hopefully then the ecosystem within the hydroponics system will become symbiotic to the roots of the plant. Good luck and happy growing!