Archive for the ‘Mold’ Category

A piece of left over cheddar cheese  was left in the refrigerater since our last field trip a few weeks ago.  A layer of white cheese mold have been growning on the surface.

Cheese Mold under Stereo Microscope

Cheese Mold under Stereo Microscope

A very dense white/green cheese mold

Cheese Mold Malachite Green

Cheese Mold Stained with Malachite Green

Some molds were scrapped off from the cheese and shaked in a vial with 2mL water.  The mixture then stained with Malachite green.


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I left a piece of rotten peach indoor.   A couple days later, I noticed very dense of mycelia were growing on it.  I put it under the microscope, there are may spore producing structure on the tip of the stalk.

Monila fructicola at 40X under stereo microscope. The black dots are the sporangia of Monilinia fructicola.

Sporangia of Monilinia fructicola at 400x. The specimen is stained with Malachite Green.

A sporangium of Monilinia fruticola at 400x. (The photo was cropped to show better details.)

The original post of the Peach Brown Rot Monilinia fruticola

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Brown Rot is a serious disease for peach trees.  This disease is caused by fungus, Monilinia fructicola.  The M. fructicola can infect flowers, shoots, fruits and branches.  Typical disease symptoms induced by M. fructicola include blossom and twig blight, cankers, and a fruit rot.   Brown rot on the peach typically develops rapid brown necrosis.  Under favored condition, the entire fruits can be rotten within 48 hours of infection. 

M. fructicola over winters in dried infected fruit called peach mummies or in infected branch cankers.  Mummies can either remain on tree or scatterd on ground.  Both may produce spores which infect blossoms and young fruit in the spring.  There are wo types of spore: ascospores and conidia. Ascospores are produced from apothecia, a mushroom-like structure that occurs only on mummies which have fallen to the ground and are partially covered with soil. Conidia are produced in abundance on mummies and infected twigs and may be spread by wind and rain. 

Here at Georgia, nicknamed peach state, brown rot is the serious disease for commercial peach orchard.  The peach tree in my backyard is not immuned from the disease.  There are beautiful peach blossom during the spring but what follows is the ugly brown rot and fruit droppings all over the ground. 

Peach insect bites

The symptoms on the fruits seems to start from a small insect bite where a small brown dot and clear gel like dischrage is clearly visible.

Brown Rot and Fruit Drop

The brown rot was spread to half of the fruit. There are fruits droppings every where on the ground.

peach mummy

A completely rotten peach is hanging on the tree. It is also called peach mummy.

Another peach mummy

I collected some peach infected by brown rot and slice a thin layer of skin.  Put it on my newly acquired Ample Scientific SM Plus stereo microscope with only the top light on. 

Healthy Peach Skin aT 20x

Healthy Peach Skin at 20x.

The skin of brown rot infested peach. The skin turned brown even without clearly visible mycelium.

Peach pulp and skin

Peach pulp and skin

Peach Pulp

The pulp of a peach infected by brown rot. Half of the pulp has already turned brown.

Monilinia fructicola Mycelium

The mycelium of Monilinia fructicola on a peach mummy.

A piece of peach mummy skin was sliced off and placed it in a vial with small amount of water. I gently scrap the surface with a dissecting tweezer, capped the vial and shacked for a few seconds.  A simple wet mount and malachite green stain was applied to the specimen.  The slide then observed at 400X with Nexcope CM701 compound microscope. 

Conidia of Monilinia fructicola

The pathogen that causes the peach brown rot. The picture is the conidia of Monilinia fructicola

two conidiospores formed on conidia (Monilinia fructicola)

Conidia of Monilinia fructicola

The specimens of conidia of Monilinia fructicola were stained with Malachite green.  Photos were taken with Tucsen 3.0MP CMOS microscope camera using Zeiss AxioVision 4.8 LE image capture software.  The eyepiece of the microscope was removed and replaced with Tucsen microscope camera adapter. 

Couple days after I left the rotten peach in door.  Rotten peach continued…

More web links about peach brown rot: 

University of Georgia Peach Handbook – Brown Rot

Cornell University Tree Fruit and Berry Pathology 

University of West Virginia KTFREC – Plant Disease Fact Sheet

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