Dying Golden Diosmas

Question From: 
Mark Henderson in  Greenwood,  Perth WA

 

Nature of problem: 
I have two rows of Golden Diosmas that are slowly dying off, one by one. It starts off in one or two branches and then spreads to the whole plant. They are in the same garden bed as two palm trees but some of the plants closest to the palms are fine (so far). There is also a hedge of pittosporum growing next to them which was planted at the same time and is doing well.

 

Type of Plant (if known): 
Golden Diosma

 

Symptoms of Plant Illness (please try NOT to diagnose your problems yourself): 
Plants are going brown, dry/brittle and ultimately dying.

 

Soil Type (e.g. sandy, clay or loam) OR Potting Mix Type: 
Sandy. Soil conditioner/potting mix added at time of planting.

 

How often do you water the plant:
2-3 times per week depending on how hot it is. Normally with drip feed reticulation but have been hand watering of late with the hot weather.

 

How many hours of sunlight does the plant get each day:
8 ish, a bit less in Winter. Slightly shaded by palms above for some of that time.

 

What type of plant is it:
Golden Diosma

 

How long since you planted it:
2.5 years

 

Have you fertilised? If so, with what and when:
Seasol every couple of months or so, Troforte rejuvenator in Spring, Osmocote all purpose in previous years ans dynamic lifter a few times since planting

 

Is the plant indoors or outdoors: 
Outdoors

 

What other treatments have you given the plant: 
Pruning when necessary to keep them tidy. It hasn’t been done since the hot part of summer started though. I also tried pruning off the dead looking parts when they occurred but it didn’t seem to have much effect on stopping the process. I noticed that the whole area had a lot of small white and brown moths coming from it a few months ago so I sprayed both the Golden Diosmas and pittosporums with Defender Maxguard (acetamiprid) which didn’t seem to do any harm at the time and got rid of the moths.

Upload photo if available: 
front garden bed.jpg

Other Comments: 
After taking some cuttings to my local nursery I was told that they simply aren’t getting enough water. Since changing to hand watering, and giving them a good soaking when I do it, I haven’t noticed any difference.

 

Answer:  Hi Mark,   Thanks for a very helpful set of info. You have worked very hard with your plants. The missing thing in your method is feedback from the soil. If you dig many small 10cm x 10cm holes in the soil with a gardening trowel you may discover dry areas around the dead plants. Water repellancy is normal for most soils in Australia and this means that normal watering often fails to wet the soil. So do test for these dry spots. Then make many fork holes in the soil and water with any good wetting agent. It takes months to get a water-repelling soil working again, so keep watering. Every 6 months reapply the wetting agent. The take-away point here is: plants can die due to lack of water in gardens that are watered often.