You just harvested your spinach and you just found some circular holes on it. Is it safe OK eat those leaves with holes? It happens to me all the time, especially when growing basil outdoor. Holes on all leaves, but I still eat it and you should too. Here’s why
Generally, leaves with holes are safe for consumption. in the majority of cases, holes on leaves are due to insects such as slugs, caterpillars o plant disease, harmless to humans. Only if the leaf presents signs of tears due to large animals, not insects, the leaf should not be consumed.
Although eating leaves with holes is generally safe, there are a few cases that you should watch out for (in the presence of animals). Moreover, understanding the different causes of such holes is of great importance to realize how they might affect your herbs and you. Hence, let’s dive in!
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Leaves With Holes?
Wondering whether we should eat leaves with holes is mainly a problem that has been created by supermarkets. Indeed, we got used to perfect-looking fruit and vegetables. However, up to half of the total produced food goes to landfills or animals just because, although perfectly edible, they are not aesthetically alright.
Among them, we have edible leaves with holes. Holes can be caused by a large variety of causes. They can be categorized in:
Among all the 4 possible causes, insects are by far the most likely to be responsible for your leaf’s damage. Many types of pests can affect your plants, and this is reflected in the way the leaves are damaged.
For instance, snails (very unlikely to be present in indoor potted plants, but possible if placed close to an open window facing an outdoor garden) can eat whole leaves. They leave behind a slimy trace (a kind of gelatin necessary for hydration purposes) on the leaf. This is generally harmless to humans.
However, it is not totally clear if the snail slime can transmit diseases to humans, like the well-known “Rat Lungworm Disease”. As discussed in this scientific publication from the University of Hawaii, snails are famous for being a carrier of such diseases that they took by ingesting larvae in rat feces.
Although it is unclear whether the slime is a problem, it is evident that ingesting raw snail is not a good idea. Indeed, the larvae inside the snail’s body can definitely transmit the Rat Lungworm disease as well, causing other potential issues. Although you are not thinking of eating a raw snail voluntarily, this might happen by accident. Indeed, tiny ones might be hidden beneath a leaf and pass unnoticed.
Before eating any raw leaf (even without any evident damage), check for the presence of snail/slug/slime residue and wash the leaves thoroughly. Although the risk of getting disease due to snail is very low extra care does not harm.
Aphids are another type of pests that feast on your plant leaves. These tiny, often semitransparent insects just suck your leaves nutrients (with their mouth that acts like a straw), causing the leaves to curl, making the plant weaker. In case you find numerous small tiny holes, you should look for these unwanted guests.
As discussed in the sneaky way aphids get inside article, aphids can vary in size (although very small, the size of a grain of rice) and in color. You can find them hiding beneath the leaves with also their eggs (typically white or yellow and oval in shape).
Remember, differently from snails/slugs, aphids are safe even to eat (although many might not appreciate them). Hence, even in case a few of them remain in the leaves after washing them, it is not a problem. If you do not believe, you can also check the US Food and Drug Administration here, regarding the safe level of “defects” in food. The presence of a moderate number of aphids is considered totally harmless (“an average of 50 or more aphids, thrips and/or mites per 100 grams” for the case of spinach, for instance).
However, this is true only if you did not use any chemical to treat the aphid invasion. If this is not the case, do not eat those leaves, just through them away. No point to risk any issue or allergic reaction for a few leaves.
Another unwanted companion of your potted plants might be caterpillars. Not all types of caterpillars are dangerous to your plants. However, quite a few (given that there are 100 thousand types) enjoy potted plants such as basil (cutworm, spread in North America), dill (Black Swallowtail), and parsley.
Similar to aphids, caterpillars spend lots of time chewing your precious leaf. However, the holes they create are larger and of different sizes depending on how hungry it was each time. Moreover, caterpillars are known among gardeners to release lots of droppings (known as frass) under the form of brown/black pellets. These can be found on leaves, on the potting soil, and even on your kitchen counter. Sometimes they come with the potting soil itself. In such case you might find useful the 5 easy ways to to sterilize your potting soil at home.
It is sufficient to wash under water your leaves to remove any trace of these dropping, that, up to know, have shown no negative impact on humans.
This pest, with aphids, are the most common in indoor plants. They are smaller than aphids, they live beneath the leaves by puncturing them with their mouths harpoon. Spider mites, individually, are harmless to your plants. However, they usually hang around in hundreds making thousands of tiny holes on your precious leaves.
As many gardeners have discussed across the internet, eating spider mites accidentally (because perhaps a few of them remained on the leaves) is not dangerous at all. Even their web are harmless to us.
Another familiar (and unwanted) guests are beetles, not often indoor, although still possible. Some varieties of this insect, common in North America, can eat edible herbs such as basil (such as the Flea beetles). In general, for indoor gardening, I never experienced a massive invasion of beetles, also given the limited leaves abundance compared to an outdoor garden. However, such insects can become a problem, even if in a small number for younger plants in which the loss of a few leaves might cause their death.
Beetles, usually do not leave droppings on the plant as, differently from caterpillars, are more dynamic. However, it should be noted that they often lay eggs on the leaves. Again, as in the case of the caterpillar, nothing to be worried about. Just wash under current water your leaves, and you are sorted.
In general, if you have the suspicion that an insect is feeding on your plants, just do a quick check on Google by typing “[name of the plant] eaten by” and see what results come out. This will give you an idea of what type of insects you might be facing.
To sum up: leaves eaten by insects are not, in general, a cause of concern for us. However, keep in mind that the whole plant might get weaker to the point that becomes the target of diseases (like a fungal infection that will alter the texture and chemical properties of the plants). In such a case, consumption should be avoided.
This should not be a concern for indoor gardeners, as typical plant-lovers animals such as deer, rabbit, woodchucks, and squirrels are not typical house-companions (especially a deer). However, other more common domestic animals, such as cats and rats (probably the last not wanted), can eat your plants. In this case, the leaf damage is going to be quite evident, potentially involving the whole plant being eradicated or severely damaged.
The question is, would you eat a plant under the attack of an animal? The answer is no! Indeed, this is the only case in which I merely threw away the plants. Indeed, especially in the case of rodents, their saliva and dropping (that might get confused with the soil) are carriers of serious illnesses.
The same applies to your (or any) cat. Indeed, we all know that from time to time, your cat might decide to play, chew a few of your plants. In this case, throw those plants. Indeed, as also specified by a few medical publications, cat saliva can (although very unlikely) lead to rabies and infections, especially in people with a weak immune system.
However, the major problems come from their feces, which can get confused with soil if you do not take attention. These are a carrier of acute diseases (like the famous toxoplasmosis) as also specified in authoritative publications.
Moreover, cats are really playful animals, so it is not unlikely that they might touch the leaves with their paws. Considering the number of surfaces (especially if you let your cat roam outside) that it reaches, the possibility to deposit harmful residue on your leaf is really high.
The same applies if you have a squirrel at home (do you?), or they come to visit you from time to time (happened to me when leaving in a small wooden house for a while).
Insects and animals are not the only culprits for holes in your precious leaves. Indeed, plant diseases, due to fungal infections, can cause similar damage. One of the most common is Downy Mildewones. As detailed by Janna Beckerman (from Purdue University, here), this fungal disease can affect sage and basil. The symptoms can vary within the same cultivar, but among them, holes on leaves can happen (for more detail if interested, you can check this study from the University of Minnesota).
Is this condition dangerous for you? No, it is not! As also stated by an authoritative researcher from the University of Maryland:
“It is safe to eat leaves from infected plants- the disease does not harm people. If you lose plants to downy mildew you can sow fresh seed in containers or in another part of your garden.”University of Maryland
Of course, there are many diseases (here a good list) that can seriously affect leaves. However, not many of them cause will cause holes in your leaf. Indeed, discoloration and wilting are among the most common symptoms.
However, I do personally suggest avoiding eating plants affected by a disease. Indeed, you might not know if your herb is affected by Downy Mildewones (that, as said before, is harmless to us) or other diseases. Indeed, although plant illnesses have not being proven to affect humans, they can still affect us in certain circumstances as stated in this scientific publication here:
“Viruses, bacteria, and fungi that infect plants do not usually cause infection in humans. However, a study reported that Pepper mild mottle virus may react with the immune system of humans and induce a clinical symptom . Several plant pathogens can affect humans by reducing the available food or by contaminating human food with toxic compound”.Sultan Qaboos University
Moreover, do not forget that the flavor and texture of an infected leaf will be severely affected, compromising your culinary experience or even ruining your dish. So, although such leaves are generally safe, I would avoid them.
I will be quick here. Indeed, you should not use herbicide indoors as the possibility to have an invasion from outside are very minimal. But if by any chance, you are using it, you have to know that it can cause holes on your leaves and other damages (yellowing, browning, spotting, etc…).
As stated by BBC gardening advice (very interesting, I do suggest having a look):
“Damaged food crops should not be eaten. Some herbicides remain active despite composting or stacking so unless you are sure of the contaminant,”BBC
Hence, as a rule of thumb, just throw any damaged leaves if the herbicide is the culprit.
Do damaged leaves taste good? If the damage is not due to illness, the leaves will still taste good. On the other hand, physical damages (from an insect or animal) do not affect the leaf’s flavor. However, in case of evident physical damage, the plant might be a victim of diseases that can cause ultimately alter the leaf flavor.
How to keep caterpillars away from your plants? Among the large variety of remedies, one of the most commonly adopted is a solution of water and soap sprayed on the plant. Remember to keep at a very low concentration the soap to avoid damaging the plant.