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Thursday, January 29, 2015

Fruit Tree Pruning Class in 29 Palms Saturday

I will be giving a fruit tree pruning class in 29 Palms, California,  which will cover basic pruning techniques of all major fruit trees that will grow in the Mojave Desert on Saturday, February 31, 2015, from Noon to 4 pm. Open to the public and free of charges.

A link for this event can be found here
https://www.facebook.com/events/1544245095859961/

2/2/15 - It was a great event and we all had fun. Here are some pictures taken by 29 Palms Inn at the event in the Faultline Garden.



Below are the notes for the workshop

Tuesday, January 27, 2015

Crape Myrtle Requires Additional Care in Desert

Q. I want to plant a crape myrtle tree. Will it survive in the northwest area of the Las Vegas Valley? When is the best time to plant and how should it be done? How do you care for this tree so it still looks good in this climate and soils?

A. Crape myrtle does fine here if the whole is dug wide enough and the soil is amended with a good quality compost at the time of planting. This tree is not a difficult tree to grow here but it’s not the easiest either.

Crape myrtle can handle full sun but it should not be placed in a total desert landscape surrounded by cacti and rock mulch. It will perform best in a wetter part of the landscape, surrounded by other plants and with the soil covered in wood mulch.

The three biggest issues to address are modifying the soil enough at the time of planting, mulching the soil surface with wood mulch and using a fertilizer that prevents the yellowing of the leaves occurs because of iron chlorosis.

I would not trust landscapers to plant this tree properly on their own. This tree will not do well if it’s planted in a cheap hole.

The hole does not have to be dug deep; just deep enough to accommodate the tree. But the hole needs to be dug wide. Make sure the planting hole is dug at least three times the diameter of its container or box.

The soil used for planting around the tree’s roots should have plenty of good compost mixed with it. An equal volume of good compost to native soil would be the right amount.

Fertilize once in the spring, around mid-February, with a fertilizer formulated for flowering woody plants, trees and shrubs. A rose or tomato fertilizer could be used as a substitute.

When you fertilize this tree in February give it 2 to 3 ounces of EDDHA iron chelate as a supplement to the fertilizer. Apply it to the soil and water it in.

If you want to give it a little extra attention and have it look even better than apply a foliar fertilizer a few weeks after the leaves come out. Use a product like a Miracle Gro or Peters that is designed to encourage flowering.

Make sure this tree is watered as frequently as your other woody landscape plants and with the same volume of water as plants of a similar size. They are nearly pest free.

Other questions about crape myrtle on this blog:

http://xtremehorticulture.blogspot.com/2012/05/crape-myrtle-and-mimosa-silk-tree.html

http://xtremehorticulture.blogspot.com/2012/09/fertilizer-formula-for-keeping-crepe.html



Tree Trunk Damage Best Left Alone

Q. I have a beautiful 10 foot tall oak that has provided privacy with it's wonderful light green, very dense foliage. I enclosed a picture of a rapidly expanding bark rot-looking area that seems to be circling the trunk and moving upward at the same time. Can this be stopped, cured, or is it life threatening to the tree?
Damage to trunk of oak from reader

A. From your picture, which I posted on my blog, this damaged area of the trunk near the ground seems to be on the mend. You can see the bark “rolling” in over the wound. Allow for the tree trunk to heal on its own. Pull away any rock or wood mulch touching the trunk and make sure irrigation is not too frequent.
Tree tissue rolling over large wound

From the looks of the damage, this was a “traumatic” event and not a disease. After damage like this the living layer around the damage forms a “compartment” that isolates the damage and heals over and around the wound. This reaction is normal to a healthy plant after an injury that is a one-time event and not getting worse.

At first it looked like collar rot, a disease, that was developing but I don’t think so. Just to be on the safe side, pull any gravel or would surface mulch away from the trunk a distance of 12 inches and keep the trunk as dry as possible.

If there is irrigation water applied close to the trunk, then move the source of the water a distance of 18 to 24 inches away from the trunk. When you are watering, avoid daily or every other day irrigations which might keep the soil wet.

Deliver the water the tree needs for several days all at once, not a little bit every day. Judging from the size of your tree this might be around 20 gallons at a time.

Trees of this size should receive water from drip emitters in at least four different locations under the tree canopy. If you are delivering 20 gallons and you have four emitters then they need to run long enough for each of them to deliver 5 gallons each.

In winter, irrigate about once every 7 to 10 days or possibly longer if you can determine the soil still has moisture. In summer time you might water once or possibly twice a week if you have several inches of mulch laying on the soil surface. 

Diversity of Plants Help in Butterfly Gardens

Q. I've been thinking about growing milkweed plants to help in the Monarch butterfly fight. Any thoughts?

A. I agree with you wholeheartedly on encouraging our local populations of butterflies and moths. They add a lot of beauty and grace to our landscape and provide some pollination and act as a food supply.
Butterflies can be pollinators

To my knowledge the Monarch butterfly does not pass through southern Nevada in its migration. I understand there are two migration routes; one from the Eastern population and the other supports the Western population.

The Eastern population misses us completely in its migration routes to Mexico. The Western population is restricted for the most part by the Sierra Nevada mountains.

Instead of focusing just on milkweeds I think a diversity of plant material for attracting these insects might be important. I have posted some reading material on my blog regarding butterfly gardens.
Reducing or eliminating pesticide use in the butterfly garden area would be wise. There are a number of pesticides that are harmful including two that I recommend frequently to organic gardeners: Bt and Spinosad. When considering pollinators both of these insecticides can be lethal to butterflies.

Always apply pesticides, if they must be applied, at times when these creatures are not active. This means the very early morning hours. Many of our moths fly at night so I would avoid applying pesticides at dusk if a major concern are night flying moths.

I put together some links on general information on Monarch butterflies, moths and butterflies of southern Nevada and how to make a butterfly garden. I wish you much success.

Wikipedia on Monarch butterflies

Threats to Monarch butterflies

Map of Monarch routes

Butterflies of southern Nevada.

How to make a butterfly garden in the southwestern desert of the US

Containers Add Benefits to the Balcony Gardening

Pepper in container
Q. I would like to plant roses or tree roses or possibly a shrub on my balcony in containers. They will be getting morning sun and afternoon shade. When should I plant them? Can the pot rest directly on the plate or should there be a space between the pot and the plate? I want to make sure it drains properly and I don’t want the water staining my white balcony.

A. You have a lot of flexibility in this location because they are in container soil and receive late afternoon shade. The limitations would be the total hours of sunlight the plants receive and winter low temperatures. Flowering or fruiting plants need six hours of very bright sunlight at a minimum to do well.

Best times for planting are in February through April or May. Another great time is in the fall from late September to mid-November. The winter months are okay for winter hardy plants but plants don’t establish quickly when container soils are cold.

Roses and other flowering or fruiting plants will be well as long as they get at least six hours of direct sunlight. Weight is a problem on balconies so use lightweight soil mixes that contain a large percentage of perlite or vermiculite. These types of soils need water frequently.

Mint in container

Because of weight, stay with containers no larger than 15 gallon. The plate under the container that catching the water can be in direct contact with the container with no problems.

If you are using tap water then about about 20% of the water that you apply should drain out the bottom of the container to move salts flushed and not accumulating.

You might also consider vegetables, herbs and smaller citrus such as kumquat or lime. 

Tuesday, January 20, 2015

Second Fruit Tree Workshop Scheduled for Henderson January 27

I will be holding a second fruit tree pruning workshop in the Henderson area, in the Warm Springs and Lake Mead area, on Tuesday, January 27 from 1 to 4 PM in the afternoon. The primary focus of this workshop is on citrus and pomegranates.


Other fruit trees we will discuss include almond and fig. The workshop is free to the public but limited to  25 participants on a first-come, first served basis. Registration is through Eventbrite

Register for the event here

We will also be discussing controlling the leaf footed plant bug and correcting the yellowing of leaves on citrus. I will cover all of the management aspects for these trees here in Las Vegas











Sunday, January 18, 2015

What Caused the Holes in My Tree?

Q. I noticed that woodpeckers attacked our Palo Verde tree. There are probably 60 holes around the truck and main limbs. The sap is running even though the holes are just under the surface, not deep. Any advice how to prevent further damage and do you think this can eventually kill the tree?

A. This is probably one of the sapsuckers. Sapsuckers are type of woodpecker and a couple different types have been documented in southern Nevada. Some sapsuckers migrate through the valley and others maintain a year-round presence.
Sapsucker damage to eucalyptus

They damage a variety of trees including fruit trees and many different types of landscape trees. They frequently come back to the same tree over and over.
 The only thing you can realistically do is exclude them from the tree. This means putting up some wire mesh, burlap or other barrier to keep them from the trunk and larger limbs. They will still get into limbs where it is hard to put a barrier.
I have seen the same fruit trees damaged year after year for the past 20 years and the trees still seem to be still doing well. Damaged trees repair themselves more quickly if they are in good health; watered and fertilized adequately. I know it causes damage but it seems to be not life threatening so I would let it go unless the damage gets extensive.

If this seems to be seasonal, you could try some hot pepper sprays just before they begin damaging plants. Mark the event on your calendar and time your applications accordingly.

Lantana Is Get Leggy If Not Cared for

Q. My friend has a lantana plant and the leaves look good from the top to about the bottom few inches and then they turn yellow. What might be the cause of this condition? My lantanas are getting very thin and "leggy". Do you think I should wait until December to cut them to the ground as some say?

A. These plants originate from wetter climates and richer soils. As these plants get older and woodier at the base, they tend to lose their leaves toward the bottom and keep the leaves on the more succulent stems and new growth.



Different Lantanas for home landscaping in the desert

This is worse if the plant is not in full sun or if it is very dense. Regular applications of fertilizer helps along with correctly pruning the plant. Prune these plants to within an inch or two of the soil surface in February if they are leggy. They also need plenty of water so if water is being restricted they will also look pretty bad.
Pruned Lantana 2 to 3 inches high in February if there is cold damage or it has become leggy

Lantana loves full sun and do very well provided the soil has been enriched and it is receiving fertilizer. If planted in rock mulch the soil will become mineralized or lose its organic matter content over time and the plant then does poorly.
Get lantana on a schedule every couple of months with a decent fertilizer for flowering plants. In the spring apply compost or composted chicken manure or something similar around the plant and water it in thoroughly with a hose. You want to re-build some organic matter back in that soil again.
I had several reports of grubs feeding on the roots of these plants. When this happens, the plant begins to decline. It might not be obvious to you unless you dug the plant up and examined the soil.

If you believe this could be a problem, you would apply a granular insecticide or a liquid drench around the outside perimeter of the plant. Granular organic insecticides containing rosemary and thyme oil work as well as conventional insecticides containing imidicloprid.

Climate and Soil Change the Quality of Fruit

Q. Last week I heard about a variety of apple called the Pink Pearl, not Pink Lady.  Will Pink Pearl apple trees survive the Las Vegas growing season?  Do you know where I can get a sapling?

A. I have heard of Pink Pearl apple but I don't how it will perform here. Nearly any apple tree will grow in our climate but it’s really a question of how good the fruit will be. It originated in Humboldt County, Northern California, and it ripens sometime in late August or September. In Las Vegas it might ripen a couple of weeks earlier than that.
Pink lady Apple fully ripe in mid to late November in Las Vegas

The eating quality of a specific variety of fruit is affected by the climate where it is grown, the soils and how it is managed. Pink Pearl has a good reputation in northern California but its quality is unknown in our hot desert climate. I would hate to see you wait four or five years only to find out the fruit is not good quality.

I am confident it will set fruit for you provided it gets pollinated. In its place, I would advise you to select an apple that ripens very early in the summer or in the fall months and avoid apples that ripen during the hot summer months. My experience with apples that ripen in July through August here has not been promising. 

Avoid Bad Haircut When Pruning Rosemary

Q. I have a rosemary bush in the front yard that's very healthy but has grown quite big in the seven years since it was planted. Is there a technique to trimming? I tried once before and it looked like a really bad haircut.
Rosemary with a bad haircut from overzealous hedge shears
A. Any older, woody plant will have its leafy growth on the perimeter of its canopy. If the plant canopy is dense, which is typical of rosemary, all of the leafy growth will be in a 2 inch layer along the outside of its canopy.
Leafy growth needs sunlight. Shade causes leaf drop and prevents leaves from developing. Dense plant canopies don’t allow sunlight to the interior. This means that the woody growth in the interior will be leafless, bare, naked. If you begin cutting away deeper than 2 inches then you will expose the interior, bare wood. This does look like a bad haircut.
The good thing is that bad haircuts are not permanent. New growth emerges from these bad haircut areas because of sunlight and the stimulation the plant receives when it is pruned.
Rosemary pruned around the tree

Shaping plants should begin when they are young. You cannot wait until they are several years old to begin shaping them unless you are willing for that plant to have a bad haircut for a while.
Pruning rosemary depends whether you want it as an ornamental or you plan to harvest the rosemary for cooking. If you are harvesting rosemary for cooking you want to harvest soft succulent growth.
Alternatively you can harvest the woody growth and strip the leaves off. Commercially pruning is done with a shears because it is faster. Again, if you cut too deeply with a shears it will look like a bad haircut.
After pruning always make sure there is enough warm weather for regrowth to occur. Water and fertilize the plant to stimulate new growth and recover from pruning.
If you want your rosemary to be an ornamental, it can adhere to any shape you want to give it. It can be sheared or it can be pruned with a hand pruners. During this last holiday season we saw upright rosemary pruned into small Christmas trees available at nurseries and garden centers. Just don’t cut the plant too deeply.
Rosemary pruned more formally like bangs in a haircut

I prefer a more normal look. This is done by reaching deep inside the plant and removing older wood with a hand shears. By reaching inside to make cuts they are hidden by the remaining growth. If you prune like this, it will never look like the plant was pruned; just smaller.
Rosemary pruned informally


Look for the longest growth, follow the stem back inside the canopy to a place where it joins another branch. Cut and remove the longer stem and leave the shorter one. This would be done in several places each year to keep it restrained.

Pick the Right Variety of Roses for the Desert

Q. I have some of these roses that are the kind that they said are ground cover type but they did very poorly in the Summer, when it was hot. Now I have planted them in the shade and they leaves are turning white then falling off. Could it be that these expensive roses from the Cal coast will not do well here? My other roses are looking great now and getting higher and higher.  These ground cover roses have never looked or done well.

A. Some of the best roses available to us are from Weeks Roses http://www.weeksroses.com/ out of Ontario, California. 

Actually this is a very good climate for roses. The very worst time of the year for them is Midsummer. When planting roses they need full sun and lots of soil amendment at the time of planting. They benefit from 2 to 3 inches of wood chip mulch on the surface of the soil surrounding the plants. 

They don't have a lot of pest problems like they would in wetter parts of the country but in the shade you might expect powdery mildew. Powdery mildew will cause the upper surface of the leaves to turn white and fall from the plant. Powdery mildew seldom occurs if roses are growing in full sun and if they are irrigated through drip irrigation, not overhead irrigation. Overhead irrigation encourages the development of powdery mildew on rose leaves and flowers.
 
Powdery mildew of roses
When selecting roses stay with recommended varieties for the desert. This list of roses can be found on the weeks roses website at http://www.weeksroses.com/_RoseInfo/climate.html


Saturday, January 17, 2015

Fruit Tree Pruning Workshop Saturday AM January 24

Location: South Jones and Patrick Lane area. Exact location will be sent to participants after they register for this class on Eventbrite. There is no fee for this workshop.

Eventbrite - Fruit Tree Pruning Workshop
Older and fruitful Gravenstein apple
 Limited to 25 people only due to the size of the yard. I will be demonstrating how to prepare your equipment, make correct pruning cuts and how to prune apple (20+ years old and one young one), apricot (5 to 7 yrs old), peach (3 to 5 year old), dwarf peach (container), fig (3 to 5 yr old) and pomegranate.(3 to 5 yr old). Location is a residential property in the Southwest of the Las Vegas Valley near South Jones and Patrick Ln. (north of CC 215, southern part of the loop).
Older and fruitful apricot


Tuesday, January 13, 2015

Viragrow Delivers! : Apply Oil Now for Decreased Pest Problems in Summe...

Viragrow Delivers! : Apply Oil Now for Decreased Pest Problems in Summe...: Why play catch-up this summer? Take care of pests now. Oils sprayed on fruit trees, landscape trees and shrubs will reduce pests this season...

Viragrow Delivers! : Fixing Yellow Citrus Leaves

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Viragrow Delivers!

Viragrow Delivers! : January Todo Suggestions From Viragrow

Viragrow Delivers! : January Todo Suggestions From Viragrow: Here are two suggestions from Viragrow  to do in your home landscape or garden area this time of year. Revitalize your "tired&quot...

Monday, January 12, 2015

Viragrow Delivers! : Do You Need Some Free Advice?

Viragrow Delivers! : Do You Need Some Free Advice?: We have Bob Morris, horticulture and garden columnist for the Las Vegas Review Journal, the View, his own blog (Xtremehorticulture of the De...

I Am Looking for Fruit Trees to Prune

I want to try something different this year.

In previous years I conducted fruit tree pruning workshops at a university facility. This year I would like to try something different. If there are homeowners who would like to cooperate in a community fruit tree pruning workshop in their home landscape, I would be interested in pursuing it during the month of January. We can talk about large fruit trees but I am not prepared to climb them for demonstration purposes.

Interested parties can contact me at Extremehort@aol.com and we can exchange phone numbers.

Requirements.
  • Fruit trees should be between newly planted up to 5 or maybe even 7 years old.
  • Home landscapes should be open to the invited public.
  • Permission to prune fruit trees and use them for demonstration purposes.

How Do You Sterilize Pruning Equipment?

Q. You often discuss the need to "sterilize" your garden tools to prevent transfer of disease. How do you "sterilize" these items?

A. A. What I mean by “sterilize” is exactly what is meant to a medical doctor and for some of the same reasons. Not sterilizing pruning equipment before its use is a terrible oversight. People overlook cleaning and sanitizing equipment because people don't understand why it is needed.
99% of the time unsterilized equipment is not a problem. It’s that 1% of the time when it becomes a problem. These are the times I receive questions about the dieback in olive, mulberry, silk tree and perhaps even ash trees.

Diseases are transmitted. Several important diseases are transmitted on pruning equipment. These include sooty canker (fungal disease of mostly ornamental plants), fire blight (bacterial disease of
Mimosa or silk tree die back due to Verticillium wilt.
many ornamental plants and fruit trees), crown gall (bacterial disease of many woody plants), slime flux (bacterial disease of many plants), Exocortis (viroid disease of citrus and tomatoes), bacterial spot (Xanthamonas, a bacterial disease), sudden oak death (fungal disease), figure mosaic virus, rose mosaic virus, tobacco mosaic virus, Fusicoccum viticolum on grape (fungal disease), Pierce's disease of grapes (5% transmission rate, bacterial disease) and others. I did not include tropical plant diseases like papaya ring spot virus and banana wilt.

Sooty canker on ash.
Cut flower growers and florists also realize the importance of sanitizing knives and pruners to prevent infections from entering the cut flower and promoting its longevity.

Whenever we enter fresh plant tissue with a pruning shears or saw the equipment needs to be sharpened, cleaned and sanitized. Adjusted and sharpened pruning equipment provides a narrow point of entry which minimizes plant damage around the cut. The concept that gardening tools should be kept clean, adjusted and sharpened is less controversial since this makes sense to people.
Equipment should be adjusted, sharpened and sterilized at the beginning of a pruning day. Equipment used for pruning should be sterilized for the same reasons we sterilize hypodermic needles and scalpels. Several important diseases are transmitted on pruning equipment. You can read more extensively about this topic this week on my blog.
Sanitize and sterilize pruning equipment. Here I am using an alcohol wipe after cleaning, sharpening and adjusting the blades.
Unlike a medical procedure which usually enters the body in one location, pruning involves entering the plant multiple times at different locations. So when pruning we must be concerned about transmitting a disease from plant to plant and the possibility of spreading a disease on the same plant to multiple locations.
If trees are healthy, then there is no reason to sterilize or sanitize pruning equipment between cuts or between trees. If the disease is present or you suspect a disease, sanitize between every cut to prevent the disease from spreading within the tree.

Sterilizing methods have been researched and there is some disagreement about what works best. Sterilizing solutions recommended include household bleach, Pine-Sol, rubbing alcohol, trisodium phosphate (TSP), and household disinfectants. 

Household bleach (ex: Clorox): 25% solution (1 part bleach + 3 parts water)
Pine oil cleaner (ex. Pine-Sol): 25% solution (1 part cleaner + 3 parts water)
Rubbing alcohol (70% isopropyl): 50% solution (1 part alcohol + 1 part water)
Denatured ethanol (95%): 50% solution (1 part alcohol + 1 part water)
Trisodium phosphate (Na3PO4): 10% solution (1 part Na3PO4 + 9 parts water)
Quaternary ammonium salts: use as directed on product label
Household Disinfectants (Lysol, etc): full strength

Personally, I have used alcohol and even a cigarette lighter when nothing else was available.
By the way, bleach can be very corrosive to steel. When using bleach, oil your equipment at the end of the pruning day.

Sterilizing and sanitizing solutions have a life span. Dispose of these solutions at the end of the day and reformulate them again when needed. If there is a lot of pruning and equipment is particularly dirty, then sterilizing solutions will need to be reformulated more frequently. 

One excellent method that reduces disease transmission from a piece of equipment is air drying it.  Unfortunately, when you are pruning the cuts are made fairly rapidly and the blades never really have a chance to dry between cuts which increases disease transmission potential, particularly bacterial, viral and viral-like diseases.

How often should you sterilize equipment? Equipment should be adjusted, sharpened and sterilized at the beginning of a pruning day. If trees are healthy then there is no reason to sterilize her sanitize pruning equipment between cuts or between trees.

When you encounter a tree that is diseased or you are not sure if it does have the disease, I would recommend sanitizing between every cut to reduce the potential from spreading it within the tree.

Workers who are moving between properties must sterilize equipment between properties at a minimum. They should be taught that if a tree or shrub looks unhealthy, they need to sterilize between cuts. This is when a rag for wiping off debris and cigarette lighter that can fit into your pocket becomes handy. Any attempt is better than no attempt.

Root pruning. Sometimes I recommend pruning roots of plants. When cuts are made on roots of plants it is important to keep the pruning cut exposed to the open air for 24 to 48 hours before allowing it to come in contact with the soil again. This helps prevent disease transmission from the soil to the plant of soilborne diseases which are numerous.

Encouraging Monarch Butterfly in the Mojave Desert?

Q. I've been thinking about growing milkweed plants to help in the Monarch fight. Two varieties look worth pursuing Asclepias EROSA and SUBULATA. Any thoughts?

A. I grew up in the Midwest and in the path of Monarch butterflies migration routes to Mexico. In fact, as a boy I volunteered to monitor Monarch butterflies for a research study done in Canada back in the 1960's.

After moving to southern Nevada I have not seen any Monarch butterflies in the 30 years I've been here in the Las Vegas Valley. My understanding is there are two migration routes; one from the eastern population of Monarch butterflies and one from the Western population.

Map of Monarch butterfly routes

The eastern population misses us completely in the Western population is pretty much restricted from us by the Sierra Nevada Mountains.

Encourage and sustain local populations. I agree with you wholeheartedly on encouraging our local populations of butterflies and moths. They had a lot of beauty and grace to our landscape and provide some pollination and a food supply. Instead of focusing just on milkweeds I think a diversity of plant material for attracting these insects might be important.

Be careful of pesticide use. Also, reducing or eliminating pesticide use in the butterfly garden area would be wise. There are a number of pesticides that are harmful including two that I recommend frequently to organic gardeners: Bt and Spinosad. When considering pollinators both of these insecticides can be lethal, in particular Spinosad to bees.

Always apply pesticides, if they must be applied, at times when these creatures are not active. This means the very early morning hours. Many of our moths fly at night so I would avoid applying pesticides at dusk if a major concern are night flying moths.

Further reading. I put together some links on general information on Monarch butterflies, moths and butterflies of southern Nevada and how to make a butterfly garden. I wish you much success.

Wikipedia on Monarch butterflies
Donate to Wikipedia

Threats to Monarch butterflies

Butterflies of southern Nevada.

How to make a butterfly garden in the southwestern desert of the US

Time of the Year for Holes to Appear in Trees

Q. I noticed that the woodpeckers have attacked our Palo verde tree. There are probably 60 holes around the truck and main limbs. The sap is running even though the holes are just under the surface - not deep. Any advice how to prevent further damage and do you think this can eventually kill the tree.

A. The only thing is exclusion and putting up some wire mesh to keep them from the trunk. They will still get into the lower limbs since it is hard to put wire mesh there.

Sapsucker damage to apple (above) and eucalyptus, aka gum (below).
I have seen our fruit trees attacked, the same ones, year after year and the trees still seem to be doing well. I know it causes damage but it seems to be not life threatening so I would let it go.

You could try some hot pepper sprays just before they begin damaging plants. Mark the event on your calendar. They are migratory so putting on some sprays might discourage them and force them on to your neighbor’s trees.