i have just discovered this white coating on one of my raspberry plants.
Looks like some sort of fungus to me, but when i searched the Internet for raspberry diseases
nothing that even remotely looks like this popped up.
The Plant is in a container with earth/compost mix, has been growing quite healthy the last
weeks since i got it.
Can anybody tell me what this is?
Should i cut the branch off?
It looks like powdery mildew. Here's a website I found with similar pictures and some info:
https://pnwhandbooks.org/plantdisease/host-disease/raspberry-rubus-spp-powdery-mildew "Podosphaera macularis (formerly Sphaerotheca macularis), a fungus. Powdery mildew is occasionally a serious disease on foliage, new canes, and fruit of red raspberry in the Pacific Northwest. It also can infect 'Loganberry' leaves. The fungus overwinters as mycelium in dormant buds of stunted cane tips or as chasmothecia. Optimum conditions for spore germination and infection are 65°F to 80°F with relative humidity of 97% to 99%. In May, leaves develop lesions that produce fungal spores that are blown to healthy foliage. In June small, secondary-infection lesions appear on vegetative tissue and developing fruit."
I bough the plant in a hardware store this year, and the affected branch sprouted from last years woody part of the plant.
I cut them away along with some parts of the wood, and really felt sad afterwards
Now i am in dillemma:
I bought a lot of raspberry plants to grow them on my balcony for nusery stock,
so that i can plant them on my plot once the situation allows it.
I am not sure if this is feasable anymore...did all the plants on the balcony get infected by now?
Should i trash them and start over to avoid bringing disease to the plot?
I think it would break my heart, but planting them on the plot just to next year discover that i introduced
Or is powdery mildew so common that it would show up at some point anyway?
reagarding the cure:
Milk probably works because of the bacterial life in it (the links states fresh milk was used).
The Link also says, that the spores don't germiante when the foilage is wet in general.
I think i will go for the actively aeriated compost tea and spray all of the plants,
hoping that the disease does not propagate.
If raspberry canes develop powdery mildew, remove the canes down to the roots during the dormant season. Infected canes of berries and grapevines have distinctive weblike russetting. Remove infected prunings from the garden area and destroy them.
Does that mean i should cut away all growth from the same rootstock?
You don't need to abandon the plants. Powdery mildew is widely present out in nature and can be treated fairly easily. Aeratedcompost tea can be a great tool (though I find it to be a better preventative than a cure for an outbreak), I think the simplest spray to fight it is water pH'd up to 10-11. You should be able to find natural pH up that is made of potassium bicarbonate and there's a company I've seen called green cure (?) that sells a super fine powder of potassium bicarbonate expressly to be used as a foliar fungicide.
The other big gun in combatting pm is bacillus thuringiensus, its a bacteria that can be present in compost teas but you can also buy it isolated in liquids that you mix.to make a spray. And the last thing that I've seen work is using a spray based on a combination of vegie oil, rubbing alcohol, and soap. You can probably find recipes online or there are a number of products premixed available. That is my least favorite option and I would like it less for use on actively fruiting plants, you have to be very careful to either spray that in the late evening or very early morning because it can cause severe photo toxicity.
The main thing I would consider is pruning to keep enough space for good.airflow. where I live pm is just around, we see it on maple trees and wild berries every year so having something like highly alkaline water or BT on hand to deal with an outbreak is crucial and spraying preventatively with compost tea and keeping the plants healthy and open to airflow handle a lot of it. Its not a death sentence for.your plants by any means though
s. lowe wrote:
And the last thing that I've seen work is using a spray based on a combination of vegie oil, rubbing alcohol, and soap. You can probably find recipes online or there are a number of products premixed available. That is my least favorite option and I would like it less for use on actively fruiting plants, you have to be very careful to either spray that in the late evening or very early morning because it can cause severe photo toxicity.
you can just skip the soap and alcohol and use the oil. any oil, though you can also get "horticultural oil" for more $$, but any oil thats cheap will work. JOJOBA oil is one i have heard people using.
the PM on the west coast is intense, it's so everywhere in the pacific northwet.
some things that help - prune a lot, remove the infected prunings, let lots of airflow by again pruning, and importantly - water the ground and not the plant. if the rain waters for you you obvioously cant help it, but if you do ever water dont water the leaves, only water the ground for the roots.
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