vegetable diseases

Giving Up On Plants; or, When to Commit Plant Murder

Erica1 Comment

I think we’ve all been there. Everything else in the vegetable garden is going well, growing as it should, producing bountifully, getting the better of challenges. And then there’s the one plant that just… isn’t. (Or more than one that just aren’t.) Maybe, though, given a little more time, a little more fertilizer, a little more effort, a little more love… it might pull through? Or is it taking up space for no reason? Worse, is keeping it around bad for your more successful plants?

When, in fact, is it the right time to commit plant murder?

I can’t help joking, but of course we all hate killing plants that we’ve tried hard to nurture, maybe even growing them from a tiny seed. But let’s face it, there’s only so much space in a garden, and the season will be over soon. We don’t want to waste the time and square feet that we have. Most of the plants in an edible garden are annuals, and with these we need to make decisions soon. With perennials, maybe you can wait until next year to see if conditions improve.

How do you figure out when and if you should pull a plant out of the garden? Well, it’s like a detective story in reverse; first, you need to be an investigator, and then a potential killer. Find out what’s wrong with the plant; assess how bad the problem is and what the consequences might be; and then make a decision based on the facts.

The HGIC website is a good place to start. If the plant in question is a vegetable, I suggest starting with the Vegetables Grown in Maryland page, select your vegetable, and visit the “Growing ___ in a Home Garden” article. From there, you can explore the list of potential problems. If you can’t figure it out from there, or from more searching online, you can contact the Ask Extension team, or ask your county’s Master Gardeners.

The problems you might encounter with plants include:

PESTS

Pest problems are often fixable. Follow the advice given at HGIC or on other regional Extension websites, and you are likely to be able to control the pests sufficiently to get a crop. However, there are a few instances where giving up on the plant is a better option.

  • The pest has killed the plant or come close to killing it. For example, squash vine borer can take out a squash plant in days, and if you don’t remove the pest in time, or it has destroyed most of the main stem, you will not be able to revive the plant. Flea beetles can eat most of the foliage of young eggplants, to the point where they can’t survive. But don’t jump to the conclusion that a few holes mean a devastating invasion.
  • The pests keep coming back even when you remove them. This happens often in community garden situations or when you have close neighbors growing the same plants. Maybe you can work together to get rid of the pests, but if that’s not an option, you might consider switching to a less susceptible crop.
  • There is a solution, but you can’t implement it right now. This is particularly true of animal pests—maybe you need to fix a fence or fill a hole, and it’s best done in the off-season. Or you have overplanted a bed, making it difficult to reach plants to remove pests. The easiest fix may be to remove the temptation and limit the pest’s options in the process.
A leaf of a squash plant with holes and yellowing from squash bug feeding.
Squash bug damage in plants I couldn’t get to because I overplanted my small garden. Photo by Erica Smith

Remember that not dealing with insect pests as soon as possible means that they are able to complete their life cycle and make more pests! If you do remove a plant that is infested, try putting it in a black plastic trash bag and leaving it out in the sun until the pests are dead. That way, you haven’t just chased them off to attack another plant. You can then put the bag in the trash or even add the contents to your compost if the plant isn’t also diseased. Speaking of which…

DISEASES

If you suspect a plant disease, diagnose it and read up on its prognosis. Does it kill a plant fast, or is it slow-working? How lethal is it and how fast does it spread? Again, it’s likely you can keep plants going for a while, for example with a common fungal disease like early blight on tomatoes, but there are cases where plant removal is advisable. If you do pull plants, put them in the trash rather than adding the debris to your compost.

  • Diseases that spread quickly. If you see the disease spreading to other plants, and it can’t be stopped by removing affected foliage and other plant parts, you may need to pull the plants that are diseased. This is especially true in truly destructive diseases like late blight (luckily, this is uncommon in Maryland!), but also with more common issues like bacterial leaf spot, which has devastated some of my recent pepper crops. Remember, most diseases are specific to particular species or families, so you don’t need to pull out your whole garden because one type of plant is affected.
  • Diseases that will prevent a plant from producing. Examples include bacterial wilt that kills a cucumber overnight (easy call), or mosaic virus that lets a squash plant continue to grow but will kill it before it has any viable fruit (harder to make the decision to pull). In perennial plants such as fruit trees, you may lose a crop one year but not the next; on the other hand, if the disease comes back for several years running despite treatment, why are you still trying? (It took me a couple years of fire blight on quince to decide I wasn’t meant to grow it.)
  • Multiple factors, including disease. A disease alone might not be enough to make you decide to pull a plant, but if it’s also battling pests or drought, or producing very little for some other reason, it might not be worth keeping.
A red bell pepper with rotten spots on the skin.
This pepper damage was likely caused by bacterial leaf spot. Not worth keeping the plants going if the result looks like this! Photo by Erica Smith

OTHER

  • Failure to thrive. This is a generic term for “just not cutting it”: looking puny and sad. Maybe the seed you grew this plant from was the worst one in the packet; maybe it got stressed from being in a pot too long; maybe the soil conditions in that particular spot are poor; maybe we’ve had crazy weather and the plant just can’t cope. Some TLC and fertilizer may help, but not always.
  • Bolting. Cool-weather crops often last into the summer, but there’s always a point when they want to go to flower, and no amount of pruning will stop it.
  • Failure to produce correctly. Maybe the plant looks healthy but it isn’t making what it’s supposed to make. Root vegetables that don’t make roots; beans that don’t bean; broccoli that won’t head up. A little extra time and some fertilizer may help, but possibly not. Pull the plant; do a soil test and plan an appropriate fertilizer regimen next year; look at conditions generally (enough sun? enough water?).
  • Need the space for something else. In a small garden, we sometimes have to make choices about what hangs in there and what gets ousted. If you want to grow kale and there is nowhere else to put it but where the tomato plant is covered with early blight and producing many fewer fruits, it may be time for the tomato plant to go.
A weak looking pepper plant with only 1 small fruit starting to grow.
This fish pepper has been looking sad all season. Might be a soil issue, or stress due to root crowding in the pot. Or something else. I still don’t want to pull it out, so I gave it some fertilizer and a pep talk. Photo by Erica Smith

In general, remember that failures are a learning experience! Sometimes we learn about a fundamental flaw in our garden or in our practice; sometimes we learn that a particular plant isn’t for us (but give it another try first!); sometimes we can just chalk up failure to a bad year or one fixable mistake. Pulling a plant is also an opportunity to put another plant in its place. (Probably not one of the same species, because the problem may affect it too.) Succession planting is made easier by thoughtful but relatively quick decision-making; get out that sick squash and you may still have time to put some bush beans in, or to get the space ready for fall planting.

And as gardeners, we always continue to hope things will be better next time!

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Cleaning up the vegetable garden in fall

Maryland Grows2 Comments

With the first frost of autumn hitting many areas of Maryland, this is a good time to think about cleaning up your vegetable garden, if you haven’t already done so! Below are some hints to getting this job done efficiently and well, and some distinctions between the vegetable garden and the rest of your yard to keep in mind.

First, maybe you still have seasonally-appropriate plants growing – in which case, congratulations! Whether they are cover crops or cool-season vegetables, keep them watered as needed and remove weeds. We’re past the point where you have to worry about most insect pests, so the lightweight summer row covers can come off the brassicas, but you may want to replace them with heavier row covers to keep the plants a bit warmer and protect them from wind. You’ll have less frost damage that way, and can keep your veggies alive longer into the winter.

Summer vegetables, however, are toast. In some recent years we haven’t had frost until later in November, and I’ve seen lots of gardeners keep tomatoes and peppers growing up to Thanksgiving. My attitude is, why bother? You may still get some produce, but the quality and flavor will not be great, and then you’ll have to do cleanup when it’s really cold. Just pull the plug. Of course I have a small garden, and if I want to plant any fall veggies, the summer ones must vacate as soon as they start to go downhill. Your mileage may vary. But it doesn’t seem worthwhile to keep a sorry plant alive for just a couple of cherry tomatoes or a wizened paprika.

So, the first step is getting old plant material out. But wait, you say – didn’t I hear that we should leave plants in the ground until spring for overwintering insects? Sure, but not in the vegetable garden. Here are two good reasons why. First, when you leave perennial plants standing in your landscape so insects can find shelter inside their stems, you commit to waiting until the weather warms in late spring to remove the dead material. That’s going to be too late for vegetable planting in many cases, especially if you rotate crops and are planning to put a spring crop where your summer veggies grew this year. There’s a big difference between a landscape of perennial flowers and an ever-changing garden of annual vegetables.

Secondly, many vegetable plants are great disease hosts. Think about it – if tomatoes and squash didn’t produce delicious food, we’d probably banish them because of how awful they end up looking and how many fungi, bacteria and viruses they spread. The longer that diseased plant material stays in the soil, the more parts drop off and bury themselves, and in some cases that disease lives on until the next year, ready to infect a new host. Ideally you should remove sick plants, or at least the affected parts, as soon as they show disease. This is really hard to do in the middle of the growing and harvesting season, but if you haven’t caught up, at least do it now.

In general, diseased plant material shouldn’t go into home compost. Some fungal diseases will be killed by thorough hot composting, so if you’re rigorous you can take the chance, or else put it on the curb and let your municipal composting do the job. Consult our vegetable diseases pages for information about each type of infection – in some cases, you should just put the plant material in the trash. If you don’t know what infected your plant, it may be best to throw it out. If the plants have been healthy, you can shred and compost them, but remember to not add mature seeds to your compost. We’ve all had pumpkin vines and tomato plants emerge from our pile, and while it’s fun to have volunteers, remember that they may be cross-pollinated and unpredictable in what they’ll produce. Also, don’t add weeds that have gone to seed, or ones that have big roots.

Rake up the surface of your beds; get all that plant debris out. Then, the final step to putting the garden to sleep is covering the soil. If you haven’t planted cover crops, use some kind of organic material to keep the soil from erosion and sprouting weeds. You’ll be surprised how many weeds will cover those beds by spring! Many “winter weeds” have thousands of seeds to spread after they go to flower, so while the bees may appreciate the early snack they provide, you will not. Covering soil also helps to protect the beneficial microorganisms and other critters that inhabit it.

Fall is a great time to add compost to your garden beds, and if the compost is really finished its breaking-down process, it can be used by itself as a mulch. However, it’s probably better to protect it and limit its potential as a weed bed by covering it with other organic materials. Leaves, shredded or un-, are a great option, if you have them around. It’s less important to shred leaves for vegetable garden mulch than for perennial beds; it doesn’t matter that whole leaves mat down and stop young plants from getting through, because you’re going to remove them before planting anyway. Sometimes whole leaves blow away, though, so it’s your choice. Straw is another great option, either from a bale (make sure it’s straw and not hay, to limit the number of grass seeds that will sprout), or in a product often known as “sticky straw” which stays in place better (the “tack” will go away in time and the straw will decay nicely). Don’t make the mistake I did and buy the straw rolls that are held together with netting! Those are meant as a temporary cover for new grass seed. I guess I’ll pull mine up in the spring and maybe I can use the netting to keep the rabbits out of my lettuce bed.

You can also cover beds with a few layers of newspaper and then put leaves or straw on top, if you’re particularly worried about weeds popping up. Whatever lightweight organic material you have will be great, or you can also use black plastic or a roll of weed barrier as a temporary cover if you have nothing else. Plastic keeps the rain away from your soil, however, and it wants the moisture. And when the mosquitoes emerge again, they will breed in the puddles where the plastic isn’t flat.

Finally, fall is a good time to repair fences and fix or add other permanent garden structures. Do it now and you won’t have to do a rush job in the spring.

Then have a nice cup of tea or cocoa and put your feet up!

By Erica Smith, Montgomery County Master Gardener. Read more posts by Erica.

Be Proactive to Prevent Vegetable Diseases

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When it comes to vegetable diseases, an ounce of prevention is worth a pound of cure. Many diseases can be stopped before they start with smart garden practices.

Spring rains cause spots, dots, and fuzzy blots to pop up in everyone’s vegetable patch. That’s fungi having fun. But whether our weather is wet or dry, fungi, bacteria and viruses stand ready to harm plants. 

So, how do you keep them at bay? Be informed and watchful. Look at your plants often to spot small problems before they get big and use the following tips to prevent disease problems.

If you have repeat offenders – diseases that show up year after year – look for disease-resistant varieties. For example, there are varieties of tomatoes labeled as resistant to both verticillium and fusarium wilt. 

Early blight is a common disease of tomatoes. Photo:  J. Traunfeld, UME

Some plants are available in certified, disease-free starts. Choose potato tubers, garlic bulbs, and asparagus and rhubarb crowns that are certified and disease-free. 

Vegetables hate soggy soil. If your garden area is wet, consider creating a raised bed to improve drainage. Or, grow in containers or move the garden to an area that drains well.

You’ve heard me preach the gospel of compost time and again. But did you know that compost actually discourages some plant diseases? Garden smart by adding compost every year. 

Help prevent disease by spacing your plants properly to encourage good air circulation. Plant labels often give spacing tips as do garden books and websites.

Warm, humid weather invites powdery mildew on squash. 
Photo: UME Home & Garden Information Center

Rain can spread soil-borne diseases, splashing infected soil up on plants’ leaves. So keep your soil covered with an organic mulch such as untreated grass clippings or newspaper covered with straw.

Fungi love wet leaves, so water wisely. Water at the base of the plant using soaker hoses or drip irrigation. And water in the morning, not the evening, so leaves dry before nightfall. 

Practice tough love. Remove infected leaves or pull entire plants if they become badly infected. It’s better to lose one bad plant than the whole row. Don’t compost sick plants: bag and trash them.

Overripe vegetables invite disease organisms. So, harvest your vegetables before they get mushy. 

A thorough cleaning of your vegetable bed at the end of the season is crucial since many diseases can overwinter in the soil. Again, if anything had a serious disease issue, bag and trash it.

If you spot a problem, e-mail your local Extension horticulturist a photo or bring them a sample to identify. Here’s a list of our county offices. We can usually get back to you in a day or two with advice.

For other growing tips and diagnostic help, visit our Home & Garden Information Center website. It has photos, management tools, and a wealth of resources. There’s even an Ask Extension link to submit gardening questions to certified horticulturists.

Enjoy your vegetable garden this year. A few seeds and transplants, some rain, sun, and a watchful eye will have you enjoying fresh, healthy homegrown food all season long.

By Annette Cormany, Principal Agent Associate and Master Gardener Coordinator, Washington County, University of Maryland Extension. This article was previously published by Herald-Mail Media. Read more by Annette.