You Bet Your Garden

What does ‘blight’ really mean?


Listen to the full show:

Mike McGrath offers suggestions for deterring animal pests, growing tangy tomatoes, what to do with chickweed, how to rehome carpenter bees, getting rid of fire ants, a good bet for shaded hanging baskets, lawn care tips for late spring, and how to fight blight in your garden.


Questions of the Week:

Last year our impatiens did very poorly, and we heard there was some problem with either the weather or a blight. So many of our plants died that we don’t know if we should try again this year. Is there a known problem or was it just a bad year?

— Michael and Myra in Allentown PA

Last September, my tomatoes were blighted. Despite growing in raised beds, being supported by nice sturdy cages and fed no chemical fertilizers, the bottom leaves began browning, then the stems; and then the fruits developed “bad spots”, which spread rapidly. It all happened at a pretty fast clip. The papers and blogs were all abuzz about “late blight”, so I pulled out the plants and threw them in the trash. I would like to avoid this blight next year. I already plan to rotate my tomatoes to a new bed. Should I also use a bleach solution on the cages to eliminate carryover? Thanks,

— Mike in Green Lane, PA

Learn how to fight blight in your garden »

Slideshow below: What does tomato blight look like? — Photos by Flickr user Scot Nelson


Highlights from show for May 25, 2013:

Protecting pear trees from animals

Judy lives in Tennessee and wants to find out who or what is eating all her pears! Could it be deer, squirrels or even bears? Mike gladly brings some solutions to her problem in ruling out the possibility of bears, since they leave plenty of damage. To detract the deer from her quarter of an acre land, he recommends getting an electric fence that is powered by solar power, which is very inexpensive. With an easy open gate, they are much better than the ones powered by electricity from the house in that there’s no worrying about whether too much of a shock is dealt to the animals.

To deter the potential raccoons, possums, and squirrels, there are simple sticky wraps and tree baffles that she can put at the base of the tree trunks. Still, squirrels may still jump to her pear tree from other trees, so in the meantime the remedy for that can be installing a simple battery powered motion activated sprinkler. Another way to prevent critters from eating everything is to prune heavily. In the winter she should thin out the branches of the neighboring trees to make it more difficult for the squirrels to jump to the pears.


Growing tangy tomatoes

John from Delaware has a garden that is 4 x 75 feet and is looking for some advice on growing sweet tangy tomatoes in his sandy soil. Mike points out that the composition of his land makes it difficult to retain nutrients for the plants, but it does drain well. Rather than tilling up the soil, he suggests getting a load of yard waste compost and layer it over the soil. He then advises John to go to a nursery and get determinant tomatoes, which are more well behaved and tend to only grow to a certain size before they stop. In picking the tomatoes, look at the listed days to maturity for each plant and get three different kinds of tomato that have different days to maturity in order to promote the variety in his garden.


Keep the chickweed

Trish in Pohatcong, NJ has a serious weed problem. There are a variety of different weeds that she is trying to remove from her garden that all seem to have their own difficulties. One of them, chickweed, Mike says can actually be a good thing to have. “Well, they are holding soil in place… Chickweed is a tremendous plant for attracting pollinators and beneficial insects. These are the kinds of tiny flowers that all the good bugs love to go to to get pollen and nectar,” he says. If Trish does decide to remove the chickweed, it should be pulled up from the ground when the soil is wet.


“Chickweed is a tremendous plant for attracting pollinators and beneficial insects. These are the kinds of tiny flowers that all the good bugs love to go to to get pollen and nectar.”

Mike McGrath


  • Chickweed
    Close-up shot of chickweed flowers

Rehoming carpenter bees

John has a log cabin that is inundated with carpenter bees in Mechanicsville, PA. To get the bees to move out, Mike explains: “You’re going to have to do something to make the wood less attractive to them. When I talk to people who have cedar homes or redwood homes, the answer is to coat the area that they’re attacking or give the whole house a coat of almond oil, which is luckily the oil of choice for massage therapists so it is available in bulk. It is somehow naturally repellant to carpenter bees and it’s also a good oil for wood. But I would think any type of new staining that you would do to the house will repel the bees, they tend not to go after wood that is stained or painted.”

Mike continues to explain that since carpenter bees are beneficial — just not in the manner that John is facing — he recommends getting pine blocks of wood from a lumber yard, drilling starter holes 5/8 of an inch in them, and then hanging them in nearby trees to give the bees a home that isn’t already taken!

Slideshow below: Building new homes for carpenter bees


Getting rid of fire ants

Carmel in Midland City, Alabama has little fire ants that are at war with her for control of her garden! She wants to get rid of them as soon as possible, however, she wants to avoid using pesticides. “These creatures have a lot of venom, the venom is very toxic, and they are very dangerous to humans, pets, and livestock. Fire ants are attracted to electricity. So I’ve always wondered if you were able to run an extension cord out to where their mound is and put one of those bug zappers, the fire ants i would think would love to march to their doom,” Mike says.

In addition, there is a well known organic mound treatment from Texas A&M University called Organic Texas Two Step that could also be used. In addition, Spinosad or Delimolene (orange peel) could be used and sprinkled around the mound. On a final note, Mike encourages that should she be bit by a fire ant, she put some Adolph’s Meat Tenderizer on a damp cloth against the bite on the skin. Just be sure that it contains papain from papayas, as this will denature the proteins in the poison.


Best bet for shade? Begonias!

Tim in Michigan is wondering what to plant in his hanging baskets that will bloom in the shade of his porch. Mike recommends his shade favorite, begonias. Mike explains: “In my shade garden, the bulk of the plants are annual begonias; you can get them in a wide range of colors … You could also grow what are called tuberous begonias, these are a little bit like dahlias, these are a summer-blooming bulb … it produces a very showy flower. The annual begonias — they produce a lot of flowers, but the individual flowers are smaller, normal size for bedding plants. There’s nothing normal about the size of a tuberous begonia, it’s out of control. It’s orchid-like, it’s dahlia-like, very showy, a lot of fun, and they’re very good at reblooming.”

Mike continues to explain that as the weather chills, the begonias do not have to be a one-time use. Tim could store dormant tuberous begonia bulbs in their hanging baskets indoors and then reused in the spring. Annual begonias can be cared for indoors through the winter and then be returned outside when the weather warms. With this approach, begonias can last years and years.


“There’s nothing normal about the size of a tuberous begonia, it’s out of control. It’s orchid-like, it’s dahlia-like, very showy, a lot of fun, and they’re very good at reblooming.”

Mike McGrath


  • Tuberous begonia
    Tuberous Begonia. Photo by Flickr user epiforums

Lawn care tips for late spring

Gwen in Bensalem, Pennsylvania isn’t happy with the state of her lawn and wants to know if it’s too late to apply weed control. Mike breaks the bad news that the window has passed for laying down pre-emergent weed control, as the best time for this is when soil temperatures are 50 – 55 degrees. However, now is a good time to apply corn gluten meal; this should be applied twice a year, in the spring and fall (never in the summer). On top of feeding the lawn, Mike advises the lawn be cut at three inches and leaving the grass clippings on the lawn. This combination of treatments will yield a healthy, weed-free lawn.

— This week’s post was written by Jolie Higazi, You Bet Your Garden Intern




  • Ruth

    We live in north central PA about 4 blocks from the west branch of the Susquehanna River. In the last couple of years, on the shady side of our house, next to the street, we have a type of weed that I cannot identify and cannot get rid of. It grows on a thin stalk and has 3 leafs. The edges are not smooth, but jagged. It is easy to pull out, but always grows back. It fills in and looks like a ground cover. We have pulled them out and mulched, but they keep coming back. Do you have any idea what it is and how to get rid of it?

    • Sarah Kaizar

      Hi Ruth — I passed your question onto Mike, and he’s not sure what the plant is without looking at it. He warns though that if it has three leaves, you should be careful as it could be poison ivy. Thanks for listening, and good luck with the mystery weed!

  • Susan Wise-Eagle

    Your chickweed looks a lot different than ours which has much smaller flowers. I’ve never seen bees attracted to it. Yours must not grow very big if you’re suggesting to leave it–we laughed when we heard you say that!! Ours here in Southeast Alaska totally overwhelms and smothers any vegetables or flowers less than 1 foot tall. The leaves do provide a spicy garnish for salads, but it doesn’t take much for that. Despite it’s name, our chickens aren’t that fond of it.

  • Susan Wise-Eagle

    Early Blight: We had been growing potatoes for years with no problems more serious than scab until a few years ago when we ended up with early blight, as confirmed by the Alaska extension lab. We finally figured out we got it from potato peels from store bought russets which my husband preferred for his Norwegian lefsa than our German butterballs, all blues, etc. It’s impossible to get a compost pile hot enough to kill either early or late blight spores. Those rotten spots we cut off the spuds were not simple rot but blight. We try to warn our fellow gardeners to NOT put potato peels in their compost and we no longer share seed spuds. We tried unsuccessfully to start over with certified seed spuds in a different part of the yard, but still have early blight. At least with early blight we still get a fair crop since the plants last longer than with late blight. Heavy fertilizing also helps. The extension agent warned us that tomatoes are even more vulnerable to blight than potatoes, so we’re very careful with what goes into our greenhouses. .

  • Mike

    Hi Ruth, I believe that your mystery weed is Goutweed, also known as Bishop’s Weed. I have been battling it for several years now. I am currently trying Mike McGrath’s recommendation for exhausting its root system by weekly weed-whacking the plant. Please see the question of the week from the May 4th show, “Groundcover Gone Bad”.



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