Knowledgebase

raspberry plants fail to fruit #804878

Asked August 05, 2022, 9:10 PM EDT

i have a large patch of wild raspberry plants they grow large canes but rarely flower and set fruit. the leaves and canes look lovely with no apparent damage or infestations. can you help me figure out how to get my raspberry plants to fruit? thank you

Otter Tail County Minnesota

Expert Response

Thank you for writing.
Without pictures, it is a bit hard but two possibilities come to mind if the plants do not appear diseased.
First over fertilizing with nitrogen as in some of the highly advertised fertilisers that suggest multiple applications can drive the plants to grow leaves instead of fruits.  Low nitrogen drives the plants to fruit.  https://www.homefortheharvest.com/raspberry-fertilizer/#:~:text=Only%20use%20the%20amount%20recommended,be%20fertilized%20in%20late%20summer.
Second, this summer's heat has caused some plants to have all male flowers--male flowers do not fruit.
https://extension.umn.edu/yard-and-garden-news/heatwave-makes-vegetables-misbehave?fbclid=IwAR3E2Q23koB8ZPejnAZd2zomMeS3DMRWyYZXO0m0a8dFoXcZL5TlG4oZM-s 

Third, we are having a steady loss of pollinators.  All insecticides (even those that claim to be targeted against pests, such as Japanese beetles, hit all insects. Cultivating for bees around your garden is helpful for fruiting.  https://www.gardeningknowhow.com/edible/fruits/raspberry/raspberry-plant-pollination.htm#:~:text=a%20natural%20wonder.-,How%20are%20Raspberries%20Pollinated%3F,quite%20a%20job%20of%20it.
Steve Miles Replied August 05, 2022, 10:34 PM EDT
thanks for the feedback. the plants may indeed be getting too much nitrogen, as the entire patch is over the site of an old outhouse!
can you suggest a way i can reduce nitrogen? do i need to move/transplant the plants to a different area?

 not too many flowers at all, male or female

my neighbor has a dozen beehives so thinking maybe lack of pollinators isn't the issue here.

thank you very much for your help

From: askextension=eduworks.com@mg.eduworks.com <askextension=eduworks.com@mg.eduworks.com> on behalf of Ask Extension <askextension@eduworks.com>
Sent: Friday, August 5, 2022 9:34 PM
To: pandnj <pandnj@outlook.com>
Subject: Re: raspberry plants fail to fruit (#0074809)
 
pa anderson Replied August 05, 2022, 10:58 PM EDT
Thank you for the note. 
I have extensive experience with outhouses and ground water.  It is highly unlikely that this is a factor given that the original pit was 6 feet deep or so and has been closed for a while.  https://goveganic.net/article217.html#further_resources

I think the more likely reason this year is the second one.  
Steve Miles Replied August 05, 2022, 11:23 PM EDT

Loading ...