In need of some advice with regard to the Casuarina Glauca in the pics attached. They were lush beautiful cousin it's but have gone to what you see over the last 4 to 5 years. They have had native fertilizer but I can say we don't water them. Any advice would be appreciated as we will give them one last try before replacing them.
Hi Ellis
The plant in the photo appears to be Casuarina glauca 'Kattang Karpet'. This cultivar is susceptible to fungal infections, Powdery Mildew being the most common especially during the cool months if the plant is getting insufficient sun.
Fungal infections can be treated with an organic products like Eco-fungicide and Neem Oil or non organic chemical like Mancozeb.
General maintenance - regular watering to keep soil moist through the growing months, avoid watering during the winter months. Fertilise in spring and early autumn, a native sustained release fertiliser will ensure the plant gets a steady stream of nutrients.