Black Spot

Hi,
we're having a lot of Black Spot this year. Normally I don't have enough to worry about, but this year the moist conditions are seeing it flourish.
I have Triforine to hit it with but prefer not to. I pick up dropped leaves and don't leave dead rose heads around. Do you think it will disappear as the summer comes on?
Barbara B

I do hope so Barbara. Like you, I have been picking off affected leaves but when I dead head I just drop the blooms at base of plants for mulch. Is it best to discard these too?

Hi Silkyfizz,
I dispose of dead rose heads, broken branchlets (rabbits) and spotty leaves in the rubbish.
I don't leave them lying around or add them to the compost heaps. When I prune, everything goes in the rubbish too.
I just think I have more black spot this year than other years.
Barbara B

I saw on the TV a very short interview with the Flemington racecourse gardener , when asked how he got the roses to look so good , he said , feeding them every three months and weekly foliar spraying of seaweed . This year i have given up on the Eco-Rose bicarb spray , and have used Eco-Neem to control the aphids when necessary and foliar sprayed every two weeks with Seasol , i have also been using Munash Rockdust and the liquid as well . So far the black spot hasn't been as bad as last year , but its early days yet , can't really tell, think i'll start foliar spraying weekly with Seasol . Big priority is a good worm farm too , when i can .....

Hi Maree,
mine get a feed of General Purpose Osmocote just after I prune, then a feed of Dynamic Lifter, Rapid Raiser or cow manure after each flush finishes. They're mulched with redgum chip.
Barbara B

Sounds good Barbara , haven't heard of Rapid Raiser , whats that one got in it ?

Barbara B wrote:Hi Maree,
mine get a feed of General Purpose Osmocote just after I prune, then a feed of Dynamic Lifter, Rapid Raiser or cow manure after each flush finishes. They're mulched with redgum chip.
Barbara B

Barbara, do you use the Dynamic Lifter which is high in nitrogen to compensate for the nitrogen that is taken out of the soil by your redgum chip?

Just to add to the red gum chip mulch , i have read that you should use soil wetter as well if you use red gum and other chips as it can make the soil water repellant too .......

The year we started the house gardens it was in the middle of the drought and we needed massive amounts of mulch (big garden). We had a couple of loads of woodchips delivered. It was used around all the native plants we had planted.
I refused to put it around my roses. The soil was already anhydrous in many places due to top soil removal and storage while the house was being built (during the drought).
The oils present in the euc woodchips leach out and tend to make the soil anhydrous.
The soil around the native plants remained more anhydrous than my part of the garden for longer.
And on soil wetters: the local garden club had a luncheon the other week where the guest speaker was Sophie from Gardening Australia. She pointed out that most (if not all?) commercial soil wetters are in fact petroleum derived. Not something she recommended for gardens....
The key to overcome this (and many pest problems) is organic matter, organic matter and more organic matter. Ie. composts, manures, and mulches like straw, hay etc.

Good infomation to have at hand, AutumnDamask, thanks for that excellent report

Hi,
when we applied to redgum chip, first we spread around a good large handful of blood and bone, then many layers of wetted newspapers, then the redgum chip. We've never had a problem with nitrogen depletion.
Rapid raiser and Dynamic Lifter are much the same.
I don't use soil wetters at all, if it's dry, I water it.
Barbara B

AutumnDamask , i have put pine chips around the natives because when i researched mulches it was said that natives like to breathe and they were best . For the roses though i use sugar cane mulch , no chips , lucerne was good but way too expensive .. The Eco company have a product called Eco- Hydrate , which sounds good and is what i would use ....

try Amgrow "Harvest" mixed with the proprietary black spot sprays for a "enhanced" spot control

Hi Finbarr,
what's in "Harvest"?
Barbara B

Harvest
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Description

Organix Harvest is a totally natural liquid fertiliser prepared from ocean fish, Tasmanian seaweed and fulvic acid. (fulvic acid is a natural component of humus that helps plants absorb nutrients) Harvest provides natural plant nutrients, trace elements and seven growth stimulants. Will help increase growth, improve flowering and fruiting and will assist in creating healthy soil. Ideal for vegetables and herbs, fruit and flowers and general garden use.


Analysis or Active

(N:P:K) 3.5: 0.6: 0.7 Plus: Calcium Magnesium Sulfur Iron Copper Zinc.


Rate

Garden Beds: Mix 50mL of Harvest Concentrate in a watering can. (9-10 litres). Apply 1 watering can per square metre of soil area. Apply before planting and then monthly throughout the growing season. Pot Plants: Mix 50mL of Harvest Concentrate in a watering can (9-10 litres).

Thanks Neptune, but why do you add fertiliser when Black Spot is fungal?
Barbara B

Thanks Finbarr

IMO, it make the plant healthier and more resilient to disease

OK, I'll try it, but the plants are pretty healthy this year with nice big blooms. I guess I was expecting you all to say it was just because of all the rain we've had.
Barbara B

On one hand I want to "do something" about the blackspot... and on the other I'm too busy ( or lazy... or both...) to actually spray.

BS hasn't killed my roses yet. (Unlike the rabbits.... )
I do have very good intentions this year though of feeding and watering them better so as to improve their health. But if we have a "normal" dry summer then I guess BS will be a passing phase for the next month.

with some of the organic foliar fertilisers; seasol/harvest etc there is a thickening of the leaf cell walls that consequently resist infection by the spores landing on the leaf. we use the same concept continuously in our production and the garden areas at Dural with pretty good results. of course good soil/mulch/position culture, along with choice genetics makes a difference too

Hi Finbarr,
we've not had a significant problem with Black Spot in the past. There does seem to be more this year. I haven't done anything different in the rose management, so wondered if I could blame the weather.
Barbara B

depends where you are Barbara, but if in doubt always blame the weather. pathogen and weed control is all about consistency in your gardening habits. get lazy at the wrong time and it takes a season to get back on track

Who is making Harvest, Finbarr or Neptune?

Amgrow..