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Extension > Yard and Garden News > January 2016

Sunday, January 31, 2016

A Pictorial Ode to Insect Flight

Karl Foord - Extension Educator, Horticulture

This is a smorgasbord of insect flight.

Magnificent Monarchs - Karl Foord

Karl Foord -  Extension Educator, Horticulture

One of my goals as an extension educator and photographer is to enable people to see things that are beyond our human physical capacity of perception. I am particularly interested in insect flight, because of my work on pollinator awareness.

Friday, January 29, 2016

Don’t Wait to Prune out Cankers and Galls

M. Grabowski, UMN Extension Educator

Black Knot Galls
A traditional recommendation in Minnesota is to prune trees in February and March. One goal of pruning during these months is to remove branches infected with cankers and galls. The fungi and bacteria that cause cankers and galls on trees overwinter in these infections. When weather becomes warm and wet many of these pathogens start to reproduce and spread the disease within the canopy and to neighboring trees.

Climate change is increasing Minnesota’s average temperature and adding days to Minnesota’s frost free season. Spring in Minnesota has been arriving earlier and is warmer. Weather data from the twin cities metro area over the previous five years reveals that in February an average of 7 days reached a maximum daily temperature over 32 F, and in March an average of 23 days reached a maximum daily temperature over 32 F.

There are several common canker and gall causing pathogen that can reproduce and infect at temperatures just above freezing, although infection rates are low at these temperatures. Black knot, a common fungal gall disease found on Prunus trees in Minnesota, was reported to begin spore release at temperatures as low as 37 F. The fungi that cause coral spot canker and perennial Nectria canker on a number of hardwood trees can begin to germinate and infect at temperatures just above 32 F. In 2012, March had 9 days with a daily maximum temperature greater than 68 F. At that temperature range, many different canker and gall causing pathogens are actively reproducing and spreading.
Nectria canker on maple -  J. Hartman, UKY
We cannot predict exactly when warm weather will arrive in 2016. To prevent canker and gall causing pathogens from reproducing and spreading, gardeners should prune out and destroy canker and gall infections while temperatures remain consistently below 32 F. When fresh new plant growth emerges from dormant buds, it will then have a clean healthy start to the growing season.

When pruning to remove cankers and galls, make the pruning cut just above a lateral bud or at a branch union that is 10-12 inches below visible symptoms of the infection.  Remove the infected branches from the area and burn or bury them.  Black knot galls left lying in an orchard after pruning were found to continue to release spores for four months.

If warm weather comes earlier than expected, pick a dry day with no rain in the forecast for the next several days to prune. Many fungal and bacterial plant pathogens release spores in response to rain, heavy dew or high humidity and need moisture on the plant surface to start a new infection. Dry weather provides a period where trees can heal the pruning wound under conditions that are less than ideal for infection. 

One Bad Apple

M.Grabowski, UMN Extension Educator

Sunken black rings of fungal growth on a stored pumpkin
If you have stored garden produce from your own garden or the farmer's market be sure to regularly inspect this produce for problems. One bad apple spoils the barrel succinctly describes how post harvest rot organisms can start in one bad piece of fruit and grow to infect everything sharing the same storage bin. Fungi and bacteria can both cause rot of garden produce in storage. Some of these organisms are weak pathogens that infect the plant in the garden but do not cause damage until after harvest. Others, like common bread mold (Rhizopus sp.) and blue mold (Penicillium spp.) are saprophytes that can easily be found in soil or plant debris.

Post harvest rot organisms take advantage of wounds like small cuts, bruises, or chilling injury to infect plant tissue. To avoid problems with storage rot harvest fruits and vegetables when they are fully mature but not overripe. Take care not to bruise or damage the fruit during the harvest process and do not store produce that is already showing signs of rot or has obvious cuts or bruises.

White mold  spreads through stored carrots. W. Brow Jr. Bugwood
Store each kind of produce in ideal conditions for that fruit or vegetable. Regularly inspect stored produce for signs of rot. Look for small round sunken spots, discolored areas, or soft tissue. Any produce showing these symptoms should be promptly removed. If caught early, the infected area can often be cut out and the remaining healthy tissue can be cooked and eaten. If the rot has taken over the majority of the fruit, remove the rotten fruit as well as all of the fruit touching it. Discard any rotten produce and use the neighboring produce in cooking as soon as possible as it has been exposed to the rot organism and will not likely store for long.

Wednesday, January 20, 2016

Forest Pest First Detector workshops in 2016

Jeff Hahn, Extension Entomologist

Registration is now open for the 2016 Forest Pest First Detector workshops!  There will be four workshops conducted during February at the following sites:

Wednesday, February 17, 2016, Marine on St Croix
William O'Brien State Park, Visitor Center
16821 O'Brien Trail North, Marine on St. Croix, MN 55047

Thursday, February 18, 2016, Mankato
Loose Moose Saloon & Conference Center
119 South Front Street, Mankato, MN 56001

Wednesday, February 24, 2016, Carlton
Carlton County Transportation Building, Meeting Room
1630 County Road 61, Carlton, MN 55718

Thursday, February 25, 2016, Fergus Falls
Otter Tail Government Service Center, Meeting Room
500 West Fir Avenue, Fergus Falls, MN 56537

Whether you would like to become a Forest Pest First Detector or are already one and would like to
Participants at a past workshop examining invasive pest
samples.  Photo: Jeff Hahn, UMN Extension
attend to receive updated information, consider registering for one of these workshops. Among the topics we will cover will include emerald ash borer, Asian longhorn beetle, gypsy moth, brown marmorated stink bug, Oriental bittersweet as well as other potential forest pests.

Workshops are from 8 AM - 3 PM. Workshop registration fee is $50 which includes lunch.  Participants must preregister and the registration fee is due during the online registration process. To register for any of these workshops or for more information, visit the Forest Pest First Detector website.

Hope to see you there!
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