How to Spray When Mantids Are in the Garden

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Mantid egg casing on a tree.

Q. Well they are back and so the battle begins.  I’m just starting to see a stinkbug or 2 and a few leaves on my squash has eggs on them.  I know just how fast those hungry buggers can suck the life out of cukes, squash, melons or whatever sounds good to them. 

This year I bought some praying mantis eggs/nest.  It’s impossible to see when they hatch and leave home so I just thought they died.  Imagine my surprise to now be finding baby mantis’s in my front and back yard....on the very same plants the squash bugs are hitting. 

So here’s my question.  To spray for the bugs or hope the praying mantis’ will feast on the squash bug buffet? 

Thoughts, ideas or opinions?  All are very much appreciated!
-Sue

A. Sue, that’s a really good question and it is one of the major difficulties we face when we try to manage our garden and fruit trees organically or as organically as possible. You have introduced an insect predator into your garden to help keep some of the "bad bugs" under control rather than to use pesticides. It is one of the cornerstones of integrated pest management or IPM. We should also be realistic about what praying mantis can and cannot do. They are not focusing on "bad guys" to help you, they are just looking for a meal. Their meals include "good bugs" and "bad bugs".

This idea works great with some pesticides approved for organic production and it does not work well for others. For instance if we use a pesticide allowed in organic production that targets a certain pest while not harming others it can work fine. An example is using Bt that kills only the larva or worms of moths and butterflies but we want to protect the praying mantis. It is totally safe for the praying mantis since it targets only the worms or larva of moths and butterflies. However, if we are realistic, it also kills the larva of butterflies which are not plant pests for our gardens.

However, if we use insecticidal soap, which is also recommended in organic production, and apply it to our vegetables or fruit trees, we are applying it is an "indiscriminate killer"; it will kill any insect on contact, squash bugs, leaf footed plant bugs, aphids, honeybees as well as praying mantis. 

When we choose to use an "indiscriminate killers" but want to keep beneficials, like praying mantis, from getting harmed, then we must direct the spray on the insects we want to kill and avoid spraying the ones we do not want to harm. This requires a lot of plant inspection on your part; looking for, identifying and targeting the "bad bugs" with the spray. 

Focusing on the use of beneficial insects as your primary method of controlling "bad bugs" limits your ability to use pesticides. You must either not use pesticides or select pesticides which will not harm the beneficial insects or direct any pesticide sprays so that they come in contact only with "bad bugs".

Another approach is to use these indiscriminate killers, such as insecticidal soaps, to keep bad insects under control and realize you will have "collateral damage". The "collateral damage" which occurs is the killing of good bugs and bad bugs with the hope that the good bugs will recover after the spraying is over. 

You also select "organic" pesticides that do as little damage to the general insect population as possible. This type of spray program limits the use of beneficial insects for any long-term control. It is really a "spray and pray" program.

Enjoy your praying mantids. They will migrate to other parts of your landscape as well as your neighbors. Visit and inspect your garden and fruit trees often. Use plants sprays when "bad bugs" are getting out of control and target your sprays on these "bad bugs".

Leaf Scorch and Thin Canopy of Ornamental Pear Probably Water

Q. We are renting and we have a tree in our front yard that is not that old.  We have been noticing that the leaves are turning a brown on the ends and not sure if it's due to a watering issue, disease or pest problem.  I have enclosed pictures of the leaves and would appreciate any help so that we can correct the issue.

A. I looked at the pictures you sent to me. It looks like may be an ornamental pear tree. The leaves that I could see certain appear to be browning due to a lack of water. The canopy of the tree also does not seem to be very full.

            My initial guess is the tree is not receiving enough water every time it is irrigated. What can be confusing is that we can see similar symptoms to trees that are also receiving too much water but in this case I think it is not enough.

I am assuming the tree is on drip irrigation and I am also assuming it is in a rock landscape. We can increase watering by increasing the number of drip emitters surrounding the tree and making sure that these emitters are 12 to 18 inches from the trunk. 

We can also increase the amount of water by increasing the number of minutes on the irrigation controller. The problem when we do this is that everything else that is watered will also get an increase in water when it may not be necessary. 

Also, this will increase your water bill perhaps unnecessarily. It is best to increase the number of emitters that way only this particular tree will get the increase in water. Another possibility, and I don't want you to do this, is to increase the number of days the tree is receiving water during the week. 

This is frequently not a good solution to a lack of water. Trees need to receive deep irrigations with lots of water, then arrest of a couple of days during the summer with no additional water, and then watered again deeply. 

You do not want to water trees daily if it is at all possible or unless they are in containers. In the meantime, take a hose and give that tree a lot of water at its base very slowly. Do this once a week and I think you will see an improvement in the number of leaves produced and the overall quality of the tree.

Can I Replant a New Tree in Mid-Summer?

Q. I planted a tree in small container in October of 2014. The tree is now 5 feet high growing well but needs water daily. Can it be presently moved to a larger container or placed in the ground or do I wait until Fall?

A. It is always a bad idea to plant from containers, either from container to container or directly in the ground, during the hottest summer months. The plant will struggle as it tries to reestablish itself, even for the best gardeners.

Wait until temperatures cool off, at least until mid-September or the first week in October. At that time you can either plant it in a larger container or put it in the ground.

Squash bugs are Wreaking Havoc in Your Garden

Squash bugs are there and they have been there for at least a month now. Please check on the undersides of older leaves of your summer squash, winter squash, melons and Pumpkins. These pictures may help you.If you are growing these plants, they are there. They are closely related to two other pasts that kind of remind you of squash bugs; leaf footed plant bug that we see commonly on pomegranate and the common stink bug which can cause dimples in fruit and buds to abort on fruit trees.

Look at these older postings on my blog:
http://xtremehorticulture.blogspot.com/2011/04/q-every-year-my-zucchini-plants-are.html

http://xtremehorticulture.blogspot.com/2014/04/is-there-anything-that-will-control.html

http://xtremehorticulture.blogspot.com/2013/05/grey-colored-beetles-on-zucchini-most.html

Why Are My Hearts and Flowers Yellow?

Q. My Hearts and Flowers groundcover is yellow green, not deep green. Why?

Click here if you want to see aptenia

A. The primary reasons would be a lack of soil improvement at the time of planting, planting in extremely hot and bright locations and not applying adequate amounts of fertilizer. Plants growing in amended soils and fertilized quarterly will have fewer problems than plants growing in soils with little or no improvement.

What you are calling Hearts and Flowers is probably Aptenia, a waxy leafed succulent with small red or purplish red flowers that have flower petals that are spiky. The most common is a variety called ‘Red Apple’ with bright red flowers.

It originates from South Africa in regions with summer rains and sandy soils. This type of climate and soil is less extreme than our Mojave Desert. This is the reason our soils must be amended with a good quality compost at the time of planting if this plant is going to look good.

Good soil drainage is a must. This plant is native to the hot climate of South Africa provided there are summer rains and sandy soils. This means this plant must be planted in soils with good drainage if it will survive. Again, soil improvement is a must.

There is an iceplant also called Hearts and Flowers but Aptenia is more commonly planted here. In our climate, Aptenia takes full sun with amended soils but may look better if planted in full sun with shade or filtered light in the late afternoon under some circumstances.

Improving the soil at planting time is a must. Yes, it is a succulent and it will do well in rock gardens but remember Las Vegas soils are an anomaly. Soil improvement is critical compared to other parts of the desert Southwest and even other parts of the Mojave Desert.

Yellowing can be caused from a lack of nitrogen so make sure fertilizers are applied at least quarterly. Use a light application of Miracle Gro or similar product and apply an iron fertilizer at the time of planting just in case the yellowing is due from a lack of iron.

Planting in Patio Containers Step-byStep

Q. I needed some advice for planting small trees or roses in containers on a balcony. Please walk me through the steps of planting in containers, when is the best time to plant, should the container be placed directly on top of a plate for drainage? I don’t want to stain my white balcony floor.

A. The first step is selecting the container. The larger the plant you want to grow, the larger the container must be to accommodate it. Weight is an issue on balconies. Make sure your balcony can support the increase in weight from a plant and container full of wet soil. Expect the container to weigh about 8 to 10 pounds for each gallon capacity, plus the weight of the container and the weight of the plant.

Gravel is not needed at the bottom of the container. Omit the gravel that many people suggest. If the gravel is not clean or sterile, you run the risk of adding plant disease to your soil mix.

Select a soil mix that is as light as possible for patios. Light soil mixes are used for houseplants and usually contain a soil amendment called perlite. Perlite is a lightweight, crushed volcanic rock which has been heat treated and expanded so that it contains a lot of airspace. Perlite adds bulk or volume to the soil mix without much additional weight. Plus it is good in holding water.

Perlite is used in light weight soil mixes. It adds bulk and improves water holding of a soil.

After purchasing the plant, gently remove it from its container and put it in a clean bucket of water. Let the roots soak submerged overnight. In the morning remove the plant from the bucket. Gently rinse off the soil surrounding the outside roots.

It is not important to remove all of the soil. Just the soil from the outside inch of the root ball. Once the soil is removed, put the plant back in the bucket with fresh water covering the roots while you prepare the container.

Never put roots of any plants in direct contact with dry soil. Put enough wet potting soil in the bottom of the container so that the top of the root ball of the new plant rests 1 inch below the top rim of the container. Using wet potting soil, fill the void between the roots and the inside of the container. Use enough potting soil so that the top of the root ball is barely visible.

Add about 1 inch of water to the container to settle the potting soil around the roots. The potting soil will “disappear” as it fills the voids among the plant roots. Add more wet potting soil and repeat this process until the soil barely covers the top of the root ball. You are finished potting the plant.

If the plant selected was for its flowers such as a tree rose, fertilize the plant with a fertilizer applied to the soil at the beginning of a growing season and once a month while it is flowering. Use a fertilizer high in phosphorus which promotes flowering.

If the plant selected was for fruit production such as a lime tree, apply a fertilizer to the soil just before flowering begins and again after harvest. Use a fertilizer high in phosphorus which promotes fruit production.

Watering will be as needed and when the soil starts to become dry. One of the easiest ways to determine this is to use a water meter sold for houseplants. They are relatively inexpensive and gives you a general idea how wet the soil might be.

Moisture meters used for houseplants can give you a general idea how dry or wet the soil is.

Another tactic is to nudge or slightly lift the container to get a general idea of its weight. Containers become lighter as they lose water. A third way is to push a pencil into the top of the soil. Pencils push easily into wet soil but are more difficult to push into dry soil.

You will water the container enough so that about 10 to 15% of the applied water runs out the bottom of the container. This is important to prevent the buildup of salts in the soil which will damage the plant. Any basin that collects water after an irrigation should be emptied soon after it fills. The container can rest directly in the basin.

Chaparral or Cleveland Sage Good Choice for Desert Landscapes