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Archive for August, 2014

Deep crack on the bottom of a large tomato. Black mold is beginning to grow in the crack.

It’s been a tough year for tomatoes.

The weather, at least in our area of the Shenandoah Valley, has been cooler than normal and fairly dry. The rain we’ve had has mostly come as heavy downpours – “frog stranglers” as my old boss used to say. We haven’t had many nice steady, soaking rains. Heavy rains, which are often associated with thunderstorms, are usually more destructive than helpful because most of the water runs off without soaking in and takes a lot of topsoil with it.

I saw on the news the other night that so far this summer, we’ve only had 15 days over 90° – the normal is 25 days by this point. Many days in July and August were in the 70’s and nights were often cool – in the 50’s and even several nights when the temperatures dipped into the mid to upper 40’s. Crazy! Nice for us but it has caused some issues in the vegetable garden.

Tomatoes don’t do well in cool weather – especially when the nights are cool. Temperature extremes (daytime temps above 90° or nighttime temps below 55°) cause poor fruit set.

First tomato harvest - 'Pruden's Purple' on July 6th and a nice big pepper, too.

First tomato harvest – ‘Pruden’s Purple’
on July 6th and a nice big pepper, too.

Our tomatoes started the season growing well; producing loads of flowers and setting lots of fruit. We have noticed that after this initial burst in June, everything slowed way down in July and August. We noticed fewer flowers and didn’t see many young tomatoes forming. The tomatoes that formed in June continued to grow and eventually ripened but production has certainly tapered off. I have heard the same complaint from other gardeners. This summer just hasn’t been favorable for growing tomatoes.

I have noticed several different problems on our tomato fruit this year but most of these are issues that I have seen in other years as well. They are fairly common tomato problems.

Growth cracks

These shallow growth cracks have healed over

Shallow growth cracks can heal.

Growth cracks develop in tomatoes when they undergo a spurt of rapid growth during ripening. This often occurs when extended dry conditions are followed by sudden heavy rain or irrigation. This isn’t an unusual situation and has occurred several times in our garden this season. As a result, many of our ripe tomatoes are showing varying degrees of cracking. Growth cracks frequently appear on the top of the tomato near the stem but sometimes when a tomato is fully ripe or overripe, cracks will develop on the bottom of the fruit. Shallow cracks will normally heal over but deeper cracks that develop can become easy pathways for disease and insects to enter and cause secondary problems.

Try to keep your garden soil evenly moist. Mulching definitely helps with this.

Anthracnose

Anthracnose lesion showing concentric rings of fungal fruiting bodies

Anthracnose lesion showing concentric
rings of fungal fruiting bodies

Anthracnose of tomatoes is a disease caused by the fungus Colletotrichum coccodes. It appears as sunken, circular lesions on ripe tomatoes. Often these lesions have concentric rings of black fruiting bodies in the center. Green tomatoes can become infected with anthracnose but the symptoms do not appear until the tomato ripens.

The fungal spores are found in the soil and on plant debris left in the garden. Tomatoes are infected when soil containing spores is splashed up onto the fruit and foliage.

Anthracnose has destroyed half of this tomato

Anthracnose has damaged half
of this tomato

Anthracnose does little damage to the leaves but can cause major damage to mature, ripe tomatoes. This disease is more common during warm, wet weather but spores can also be transmitted to the plants from splashing during overhead irrigation.

Mulching around your tomato plants and trellising or staking them to keep them off the ground will help to prevent this fungal disease. Avoid working among the plants when they are wet and harvest the tomatoes as they ripen and use them promptly.

Infected fruit should be removed to prevent the spread of the disease. Crop rotation and careful clean up of all plant debris in the fall is important for controlling anthracnose.

Cat facing

Cat facing on a large heirloom tomato

Cat facing on a large heirloom tomato

Ever find tomatoes that have funky-shaped, puckered bottoms? This is called cat facing and it is thought to result from the abnormal development of the flower bud or flower – before the fruit is even formed! The factors that lead to cat facing in tomatoes are normally environmental, including cool temperatures before and during flower formation. Hmmmm, that sounds familiar!

Other causes of cat facing in tomatoes are any type of physical damage to the flowers, herbicide damage (such as drift from nearby 2,4-D spraying), and sometimes excessive pruning of tomato plants.

Mild cat facing

Sometimes it isn’t too bad

.

Varieties that produce large tomatoes, such as beefsteaks and the large-fruited heirloom tomatoes, are more prone to cat facing than small-fruited varieties.

Normally, tomatoes that are disfigured from cat facing are still edible however they may ripen unevenly and they can be difficult to slice – I just chunk them up instead! Still delicious!

Black mold

Black mold started growing in the growth cracks of this tomato.

Black mold started growing in
growth cracks of this tomato.

Black mold is caused by various fungi (including Alternaria alternata) that attack tomato tissue that has been injured in some way. It is rarely found on healthy, unblemished tomatoes. The fungal spores usually enter the tomato where the skin has cracked or where insects have caused injury to the fruit. As the fungus grows, it creates brown or black sunken lesions which expand and eventually cause the whole tomato to rot.

If you catch it early, you can just cut out the bad patches but it’s important to remove all the soft tissue or the tomato will taste bad.

All of these problems have developed on at least some of my tomatoes this season. Fungicide sprays listed for use in vegetable gardens can help but I normally don’t bother with them. None of these diseases have caused any major damage to my tomato crop. We just harvest the blemished fruit, cut out the diseased parts, and eat them. You should NEVER can or freeze tomatoes that show signs of disease.

Even though our tomato crop hasn’t been a bust this year, the yield from our 36 tomato plants should have been much higher. I’m normally swimming in tomatoes at this point in the season. Well – at least the tomatoes we’ve harvested have been very tasty. I’ve been able to can a few batches so far and they are still coming along. Hopefully this hot spell we are in now will give them a late season boost!

Lynne's cherry tomatoes are beautiful but her other tomatoes are small.

Lynne’s cherry tomatoes are beautiful
but her other tomatoes are very small.

How did your garden do this year?

My sister Lynne in Vermont told me yesterday that her tomatoes are all really small this season compared to other years. It’s been unusually cool up there this summer, too!

She sent this photo of her recent harvest. Nice rattlesnake beans and cukes Lynne!

Until next time –

     Happy Gardening!

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Pickleworm entrance holes in zucchini

I didn’t notice the little holes when I cut the squash from the vine. It wasn’t until they had been sitting in the harvest basket on the kitchen counter that I noticed the little pile of frass (insect “poop”) on the outside of one of the zucchini that I had harvested. It looked like pale green sawdust piled just outside a small hole in the squash. When I picked it up, I noticed that there were quite a few little holes in this particular zucchini.

Hmmmm – pickleworms!

Pickleworm on pumpkin; Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org

Pickleworm on a pumpkin

Interestingly, just a few days before, I had received a post on our discussion board inquiring about the same problem with pumpkins:

How soon can pumpkins be cut from the vine? I have trouble with something boring holes in them causing them to rot if left on the vine too long.

Pickleworms (Diaphania nitidalis) are pests of pumpkins as well as various types of summer squash, cucumbers, and cantaloupes. They literally devour the fruit from the inside.

Pickleworm larva feeds on the tender flesh of a zucchini

A pickleworm larva feeds on the
tender flesh of a zucchini

These destructive pests are the larvae of a moth that doesn’t even survive in this area over the winter. They are subtropical insects and spend the winter in areas like Florida and Texas. In the spring, they migrate northward to invade vegetable gardens as far north as southern New England and parts of the Midwest. The only blessing is that it takes them a little while to make it up here so one way to avoid them is to plant squash crops as early as possible and/or plant early maturing varieties so you can harvest a nice crop before they become prevalent. That is easier to do with summer squash than with cantaloupe and pumpkins, though.

Unfortunately, pickleworms have a very short life cycle (often less than 30 days) and can produce up to 4 generations per year depending on the climate. In our area, I doubt they have more than two or three generations but this is still enough to wreak havoc in the garden.

It’s the larval stage that does all the damage. The young pickleworm larvae/caterpillars begin feeding as soon as they hatch from their tiny eggs. At first, they bore into and feed on the flower buds and the tender young stems of the plants. As these caterpillars grow, they molt several times going through 5 larval instars before they mature and pupate.

Small entrance holes mark where the pickleworm caterpillar has bored into the fruit.

Small holes mark where the pickleworms have bored into the fruit.

The major damage comes when the older pickleworm larvae bore into the fruit. The small entrance holes they make are tell-tale signs of the invasion. Sometimes you will see little piles of frass on the fruit just outside the holes. Inside, these caterpillars are voraciously consuming all the good stuff – hollowing out the interior and leaving the fruit inedible.

The other day I cut open a medium-sized zucchini and found a large green pickleworm inside. This was quite a surprise since I hadn’t noticed the entrance hole.

The caterpillar left a large cavity where it had eaten the flesh of the squash. Later, I found a smaller zucchini that had at least 5 bore holes in it so there were probably 5 pickleworms inside. Gross! I didn’t look!

Chowing down on my zucchini!

Chowing down on my zucchini!

Over the years, we haven’t had much trouble with these disgusting caterpillars. Thinking about it now, this is probably because normally by this point in the season (when pickleworms begin to be a problem), my summer squash plants have succumbed to squash vine borers and I have pulled them all out! I got lucky this year and the vine borers only got a few of my plants. So now we have pickleworms. Ugh!

I do think that the pickleworm population must be worse this year because I also found them in both of the cucumbers I just picked. That’s a first for me but I have heard of some people losing almost an entire crop of cucumbers to these nasty critters. Because summer squash is their food of choice, one suggestion to help protect cucumbers is to plant a trap crop of summer squash beside the cucumbers so that the pickleworms attack the squash and leave the cucumbers alone – this is supposed to work pretty well.

Other control methods

In our area where pickleworms can’t overwinter, the best bet is to plant resistant varieties and early maturing varieties of squash and to plant these crops as early as possible. Starting the seeds indoors and planting hardened off plants can help you get a jump on the season. That way you can usually get a nice harvest before these caterpillars become prevalent. For us, they are normally a problem later in the season. I am just now seeing them.

This cucumber is a goner!

This cucumber is a goner!

Normally pickleworms are difficult to control with pesticides because once they bore into the fruit, they are protected from sprays. Timing is critical; you have to control them when they are first hatching out.

When the buds first form and the flowers begin to open, spray the plants with Bonide Bt Thuricide or Bonide Captain Jack’s Deadbug Brew which contains spinosad. These products are normally less harmful to beneficial insects when used according to the label directions.

Pickleworms can also be controlled with Bonide Eight sprayed according to the label directions.

Always spray the plants early in the morning or in the early evening when the bees are less active. Pay close attention to the pre-harvest interval (PHI) when spraying vegetables.

Boy, am I glad they don’t like tomatoes!

Until next time – Happy Gardening!

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One whole hosta clump totally defoliated by deer

This yew was decimated by hungry deer over the winter.

This yew was decimated by
hungry deer over the winter.

The other day I was flipping through some pictures that I had taken of my sister’s gardens in Vermont and came across some photos of damage that had been done by deer in her gardens.

Most of the damage was more recent, from summer munching on her hosta but, over the winter, the deer had also browsed many of her shrubs including her yews (Taxus). The poor yews looked pitiful with just a few tufts of new growth coming out at the tips and along the branches. Luckily they have dormant buds in the bare wood so they are able to recover from this damage. They can be cut back hard, similar to the way you can prune boxwood and holly. I find it interesting that deer eat yews because these shrubs are highly toxic to cattle!

Last winter was definitely a tough one for deer because it was so cold and many areas had quite a bit of snow. This resulted in more damage than normal because they resorted to eating things that they might normally have left alone.

One gardener wrote,

Due to the extremely cold winter here in Annapolis, MD, I’ve noticed this spring that the tips of my azaleas, the bottom of my camellias, and evergreen shrubs appear to have been bitten off by deer (I have many in the wooded area I live in). The deer have never attacked these shrubs since I moved here years ago, so this damage has come as quite a surprise.

The deer browsed branches of an apple tree in our orchard

The deer browsed branches of
an apple tree in our orchard

Deer damage is especially devastating when it occurs on the spring flowering trees and shrubs that bloom on old wood (wood produced in the previous season). Often as they browse, the deer strip off many of the tender, dormant flower buds and thus wipe out much of the spring bloom.

Unfortunately, they really like rhododendron, azalea, and hydrangea! Some hydrangea, such as Hydrangea arborescens ‘Annabelle’ and the ‘Endless Summer’ series will normally still bloom even if they are heavily browsed because they bloom on new wood.

In the spring or whenever you notice deer damage, it’s a good idea to make clean cuts on the stems or branches that were chewed. Prune them back to live, undamaged wood. This will prevent insects and disease from entering through the ragged wounds left by the deer and help keep your trees and shrubs healthy. Be sure to fertilize them with a good organic fertilizer like Espoma Plant-tone, Tree-tone, or Holly-tone.

Munched daylily buds. At least there were some flowers that bloomed!

Munched daylily buds. At least
some flowers bloomed!

As most gardeners know, deer damage isn’t limited to the winter months. There are plenty of trees, shrubs, annuals, and herbaceous perennials that they just love to eat during the spring and summer.

This summer, I have spoken with so many customers that would love to grow daylilies but can’t because the deer chew off all the flower buds right when they are about to bloom. How sad! They always ask me why we don’t have the same problem here with all the daylilies we grow. It’s true that we don’t normally have an issue with deer and I’m not sure why except that there is probably plenty of other food available in the surrounding fields. That being said, I have noticed that this year we HAVE had some deer browse on our daylilies. I’ve only seen it on the edge of some of the display beds but I definitely found some gnawed off daylily buds this summer. It is not widespread so perhaps we’ve always had SOME damage and I just never noticed it before.

A beautiful hosta totally destroyed!

A beautiful hosta totally destroyed!

Hosta are another one of their favorite snacks. They can devastate a beautiful hosta garden in no time at all. In one of Leslie’s beds, there were just leaf stems remaining after the deer went through – not very pretty to look at. They seem to pick and choose the ones they eat. Many of the hosta cultivars with thick, puckered leaves seem to be less desirable than the ones with thinner, more tender leaves. Interesting that slugs and snails have the same preferences.

These large-leaved hosta were not touched.

These large-leaved hosta with
heavy texture were not touched.

So what can you do short of resorting to a 30-06 rifle?

Plant “deer resistant” plants

Echinacea (coneflower) are colorful, long-blooming, and deer resistant!

Echinacea (coneflower) are colorful,
long-blooming, and deer resistant!

Deer are a persistent and once they find plants they like, they will continue to feed on them. You can often dissuade them from munching in your garden by placing plants that they don’t like to eat throughout your beds. While no plant is entirely “deer proof”, there are many perennials and shrubs that are deer resistant and most of them are beautiful plants that you will love having in your landscape.

Typically, deer steer away from plants that have thorns, fuzzy leaves or stems, coarse or tough leaves, plants with milky sap, and plants with aromatic foliage. Be aware, however, that the resistance of plants to deer damage is often related to the availability of other food and when times get tough, deer are often forced to eat normally “resistant” plants – as evidenced by last winter!

Use deer repellents

When it's cold out, the dormant flower buds of rhododendron become irresistible to deer.

Large leaf rhododendron are
usually irresistible to deer.

Certain plants, like hosta, daylilies, tulips, and rhododendron, are “candy” to deer and are frequently severely damaged by these garden marauders. If these are planted in areas where deer are common, they should be protected by fencing or by some type of deer repellent.

There are many repellents on the market now that claim to keep deer out of your gardens. Plus – don’t forget the Irish Spring soap in the nylon stocking trick!

Regardless of the repellents you choose, our most important recommendation is to alternate repellents through the season! Deer will eventually become accustomed to most repellents and then they will no longer be effective. Switch to a different repellent every 4 weeks or so.

Sometimes you just need a fence!

Why or why don't they eat the coltsfoot and leave the hosta!

Why oh why don’t they eat the coltsfoot and leave the hosta!

Deer fencing can protect the landscaping and gardens around your home. There are many different types of fencing available and the choice depends on how large, permanent, and strong you want your fence to be. A few years ago, we had deer in our vegetable garden for the first time. I guess they finally discovered that they could jump right over the 4 foot fence we had surrounding the garden. Now we have extended the fence up to about 10 feet high using stout bamboo poles and plastic wildlife netting. So far it seems to be working well on the deer but we are still having a problem with that stupid woodchuck …

Until next time – Happy Gardening!

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