Why Do Fruit Split Before Harvesting?

Q. What causes cantaloupe melons to split before they slip the vine?

Melons splitting as they are ripening

A. Like any fruit, when the melon nears maturity and the outside rind hardens and irrigation water is “pumped” into fruit, they split. This can happen with melons, cherries, peaches, tomatoes, cucumbers, and other botanical fruits. Fruit with a thin skin like cherries are more susceptible to splitting after a rain than thicker “skinned” melons. Fruit splitting can happen soon after an irrigation when the temperatures have created a lot of stress or right after a rain.

Peach splitting on the tree

Rainwater enters the fruit through the “skin” or rind and causes it to swell and burst. It is due to an “osmotic effect” and susceptible fruits will split when nearly ripe and their sugar content is peaking. Nearing maturity is the time these fruits are full of sugar and primed for rainfall and the “osmotic effect”. “Nearly ripe” is a dangerous time for a combination of fruit and rain.

Orange split

What to do? First of all, note the variety. Some varieties are more susceptible to splitting while others are not. Secondly, harvest climacteric fruit (those fruit that continue to ripen after they are picked) early. before a rain and let them ripen protected after harvest. Unfortunately, melons are non-climacteric and do not ripen further after picking. Protect the fruit from rainwater and apply a surface mulch during hot weather.

Cupping or Rolling of Plant Leaves During the Heat

Q. Why are the leaves of my fruit trees cupping or rolling?

Leaf roll or cupping on pepper plant even though its mulched

A. Fruit tree leaves of apples, pears, pistachios, tomatoes, and other plants in full sun all day long will sometimes cause the leaves of some varieties to cup or role. Excessive irrigation and fertilizer, high temperatures, the variety of the tree or plant, overly dry soils, root damage and planting shock are some of the environmental factors that can cause physiological leaf roll in fruit trees. Over time all the leaves on the plant may be affected.

Tomato leaf (probably 'Early Girl' cupping or rolling

If your plant is showing lots of leaf roll first blame the high temperatures of summer. Leaf rolling won’t hurt the leaves as long as they remain soft and pliable. Next, be careful of irrigations. Irrigations should keep the soil consistently moist for most garden plants and not allow the soil to dry out rapidly. Apply a surface mulch to slow water loss from the soil and reduce plant stress. Woodchips, straw, shredded newspaper applied a few inches deep will slow water loss from the soil, reduce fruit cracking due to irrigation and conserve moisture.

Leaf roll of mockorange landscape shrub (Raphiolepis spp.)

Retract Your Statement About Poisoning Ground Squirrels!

Q. I am wildlife biologist and a gardener. You should retract your statement about poisoning ground squirrels as the poisoned bodies will appear in the food chain of hawks, owls, coyotes, foxes, and snakes.

Ground squirrel taking the nut from almonds by chewing the outer hull and shell

A. You are right. Poisoned carcasses of any animal can enter the food chain of other animals. It is important to make sure that individuals are following all federal, state, or local laws or ordinances pertaining to the use of a pesticide (whether it is used to kill weeds, insects, protect plants from diseases or terminate the life of a critter) and that any pesticide is used as a last resort. Make sure to read the pesticide label and follow its directions.

After ground squirrels are finished harvesting the nuts, they leave behind the hull and husk which can drop to the ground

            Ground squirrels can rob a tree of almonds overnight. One method to avoid this from happening is to harvest the nuts earlier in the calendar year and dry them in a protected location.

There are different ways to eliminate ground squirrels. Pest control companies exist that focus on “humane methods” and market these options for concerned gardeners. I would refer anyone interested to follow the advice given by the University of California regarding controlling ground squirrels (http://ipm.ucanr.edu/PMG/PESTNOTES/pn7438.html). Please remember that trapping and releasing an animal to another area is illegal in most states and potentially cruel. Check with your local laws.

Nuisance wildlife in Nevada

Bottletree New Growth Dying in Phoenix

Q. The new growth on my bottletree I bought in 2018 is dying (crusty), starting a month or so ago. After talking to the local nursery, I increased the watering and soaked it for about an hour and it now looks worse. I’m watering 6 days a week and each time the tree is getting 22 gallons.

Branch in bottletree dying back.

A. Not sure why you thought the tree looked worse after you watered it. This trees roots are sensitive to watering often and keeping the soil wet. It’s a “deserty” kind of tree, but not truly “deserty”. As a young tree, it needs about 20 – 30 gallons each time it is watered. You are watering the right amount, but the soil shouldn’t be continuously wet six days a week. That’s a mistake. Read what someone else says about this tree in the Phoenix area.

Roots Must Breathe

The roots need a chance to “breathe” after the tree is watered. Knowledgeable people from the Phoenix area suggest watering this tree only twice a month during the summer. Remember, Phoenix is a bit wetter than we are because of their summer monsoons and they get more cloud cover.

My advice is not as dramatic, but I think not giving the soil a chance to dry out between irrigations is a mistake with this tree. Starting this October, try watering less often, maybe twice a week. Apply water to the soil starting 12 to 18 inches from the trunk. This water should wet the soil all the way to the ends of its branches (canopy). This tree likes to have other smaller “deserty” plants getting water near it. Other plants help cool things down.

Apply Water Less Often but Deeper

Apply enough water so the soil is wet to a depth of about 24 inches. This takes somewhere between one and 2 inches of water so that will take about an hour or so. Then hold off on your next water application until the top four or five inches of soil starts to dry out. Then water again. This might result in watering once, twice or three times a week depending on the time of year. Watering fills the soil again with water and then wait long enough for the tree use it. The upper surface of the soil will begin to dry. This drying of the soil encourages deeper rooting of the tree and helps avoid root diseases due to frequent watering. That’s normal.

Inexpensive soil moisture sensor you can buy at any box store

...

            Use an inexpensive soil moisture sensor (like the kind sold for houseplants) and gently push it to into the soil about 4 to 5 inches deep, soon after an irrigation and in several other spots. When the soil moisture averages about “5” on its meter, water again and fill up the soil.

Bottletrees and Leaf Drop

Are Bottletrees Really Desert Trees?

Problems with Bottletrees Growing in the Desert

Bottle Trees Dropping Leaves Probably Water Related

Rosborough and Womack Blackberries Can Be Grown in the Mojave Desert

Q. I am growing Bababerries. What small berries do you recommend for our Mojave Desert climate?

'Rosborough' and 'Womack' blackberries grown at the University Orchard in North Las Vegas.

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A. Growing berries is tough in our desert climate due to summer heat primarily. Bababerry (a heat tolerant raspberry) is a good choice to try due to its heat tolerance. I have not grown it but others claim it works. 

I have had luck growing two blackberry varieties for several years: ‘Rosborough’ and ‘Womack’. I was led to this decision by a publication out of Tucson, Az, regarding some research done in Yuma. I also tried 'Brison' but did not have the luck growing it as I did the other two. Both are “thorny” and grow erect so they don’t need much trellising. Both varieties were released from Texas A and M University in 1977 with very similar traits.

Other varieties (particularly varieties released from the University of Arkansas with native American names) have not been very successful here. All that information is anecdotal as I have not tried them. 

In our climate these berries mature during the heat in May and, like figs, must be picked the same day they are ripe. So mark your calendar for picking when growing these berries. They do not keep well after they are harvested.

You can buy starts of either of these or both by mail order here.

Value of Manure in Landscapes is Not Just for Fertilizer

Q. What is the range of N-P-K value in cow manure that I see some landscapers use for grass?

Manure can be a valuable source of many different plant nutrients, good and bad microorganisms, 

and organics. It is best composted first but in a pinch you can use it raw. Just be careful.

A. The fertilizer content (N-P-K value) of steer or cow manure varies because of what they eat and how the manure is collected and processed. It is considered “low” in fertilizer content as far as fertilizers go. It would take a very small amount of bagged fertilizer to equal the fertilizer content in a ton of manure. Both manures contain about 4% nitrogen and lesser amounts of phosphorus (P value) and potassium (K value). They can both be high in salts and rich in both good and bad microorganisms.

Difference Between Cow and Steer Manure

There is a difference between steer and cow manure. Cow manure is typically derived from cows used for dairy farming. Steer manure is derived from cows fed for meat production. Steer manure typically contains more salt than cow manure and it is considered “hotter” when applying it to plants.

Value of Manure

The value in manure is due more to its potential for soil enrichment rather than its N-P-K content.  For that reason, it can be mixed into a “hot” compost pile. The heat from these compost piles will help to change the microorganism content and decrease or possibly eliminate those microorganisms which are a potential human health problem. 

Research has shown that applications of composted manure can reduce lawn diseases due to its high microorganism count. Application of dry manure is done best with a barrel-type compost spreader.

Winter Pruning of Pomegranate Helps Remaining Stems to Remain Erect

Q. Why do my pomegranate trees have large branches lying on the ground?

Young pomegranates sucker from the base every year when they are young. These suckers need to be removed in winter pruning so that 5 to 6 larger stems remain. This winter pruning and sucker removal helps build the future fruit supporting structure of the pomegranate tree.

A.  I dont have a picture of these limbs on the ground but just went through this at an orchard where I am consulting. The pomegranates were three to four years old and had not been pruned for one or two seasons due to a poorly undiagnosed disease problem (probably crown rot due to frequent irrigations and lots of wood chip mulch applied near the base). This disease problem was spread between plants through pruning. When they were finally pruned this past spring, some of the larger stems laid on the ground. 

Pomegranate dieback disease (probably crown rot due to mulch keeping the stems wet and spread on hand pruners at pruning time), Yes, you can water pomegranate too often.

This happened for a couple of reasons. First, there was ALOT of new sucker growth from the base that caused some crowding because they were young. Sucker growth slows done considerably after about 8 to 10 years of growth and an established canopy. Secondly, they were growing like gangbusters with most of that disease gone. They are flowering and fruiting heavily causing a lot of weight on the ends of these stems.

This pomegranate was not pruned every winter and got out of hand. By this age, the tree should have hand its architecture established so the fruit does not lie on the ground.

This can happen to pomegranates when they have been in the ground for a short time and not pruned regularly. Pomegranates should have emerging suckers removed from so that only five or six of the larger stems remain. Then side growth is pruned from these main stems to about knee height to help prevent fruit born on thick woody stems from lying on the ground. This results in larger fruit produced on the older and thick 5 to 6 stems remaining and fruit produced on these smaller, side, lower branches will not lie on the ground.

This pomegranate has been pruned so that five or six larger stems remain. All the smaller suckers were removed. These remaining larger stems will bare the weight of a full load of fruit in the future. The next step is to remove the side branches to knee height.

The remaining stems will begin flowering and bend toward the ground as the heavy fruit bends them over. As these stems get older, they will get stronger. New growth comes from the remaining bent stems and not as sucker growth from the base. Removing the sucker growth from the bottom encourages the remaining stems to grow strong and erect without crowding them. Removal of sucker growth must be done frequently when they are young until the new growth emerges from the larger stems and not as suckers at the base. You are nearly done. Remove side growth from any of these major stems to about knee height so the fruit produced by these branches do not lie on the ground.

Melon Splitting after a Rain

Q. What causes cantaloupe melons to split before they slip the vine?

Melons splitting can be from several things but usually applying a surface mulch on the ground to slow evaporation from the soil will help

A. Like any fruit, when the melon nears maturity and the outside rind hardens and irrigation water is “pumped” into fruit, they split. This can happen with melons, cherries, peaches, tomatoes, cucumbers, and other botanical fruits. Fruit with a thin skin like cherries are more susceptible to splitting after a rain than thicker “skinned” melons. Fruit splitting can happen soon after an irrigation when the temperatures have created a lot of stress or right after a rain.

Peach fruit split

Rainwater enters the fruit through the “skin” or rind and causes it to swell and burst. It is due to an “osmotic effect” and susceptible fruits will split when nearly ripe and their sugar content is peaking. Nearing maturity is the time these fruits are full of sugar and primed for rainfall and the “osmotic effect”. “Nearly ripe” is a dangerous time for a combination of fruit and rain.

Tomato fruit split

What to do? First of all, note the variety. Some varieties are more susceptible to splitting while others are not. Secondly, harvest climacteric fruit (those fruit that continue to ripen after they are picked) early. before a rain and let them ripen protected after harvest. Unfortunately, melons are non-climacteric and do not ripen further after picking. Protect the fruit from rainwater and apply a surface mulch during hot weather.

Leaf Rolling (Cupping) of Fruit Trees, Ornamentals and Vegetables

Q. Why are the leaves of my fruit trees cupping?

Leaf roll of tomato ('Early Girl' variety, I think) during summer heat but the leaves look fine otherwise

A. Fruit tree leaves of apples, pears, pistachios, tomatoes, and other plants in full sun all day long will sometimes cause the leaves of some varieties to cup or role. Excessive irrigation and fertilizer, high temperatures, the variety of the tree or plant, overly dry soils, root damage and planting shock are some of the environmental factors that can cause physiological leaf roll in fruit trees. Over time all the leaves on the plant may be affected.

Leaf roll of mockorange (Raphiolepis) during the heat of summer (in northern climates the common name of mockorange is a different plant, Philadelphus). Had me confused for awhile.

If your plant is showing lots of leaf roll during the summer first blame the high temperatures of summer. Leaf rolling won’t hurt the leaves as long as they remain soft and pliable. Next, be careful of irrigations. Irrigations should keep the soil consistently moist for most garden plants and not allow the soil to dry out rapidly, a balance between watering too often and not watering often enough. Apply a surface mulch to slow water loss from the soil and reduce plant stress. Woodchips, straw, shredded newspaper applied a few inches deep will slow water loss from the soil, reduce fruit cracking and leaf roll due to irrigation and conserve moisture. Sometimes its just damn hot!

Ground Squirrel Damage vs. Poisoning the Food Chain

Q. I am wildlife biologist and a gardener. You should retract your statement about poisoning ground squirrels as the poisoned bodies will appear in the food chain of hawks, owls, coyotes, foxes, and snakes.

Ground squirrel harvesting of nuts from almonds

A. You are right. Poisoned carcasses of any animal can enter the food chain of other animals. It is important to make sure that individuals are following all federal, state, or local laws or ordinances pertaining to the use of a pesticide (whether it is used to kill weeds, insects, protect plants from diseases or terminate the life of a critter) and that any pesticide is used as a last resort. Make sure to read the pesticide label and follow its directions.

Ground squirrel looking for handouts at Hoover Dam

            Ground squirrels can rob a tree of almonds overnight. One method to avoid this from happening is to harvest the nuts earlier in the calendar year and dry them in a protected location.

Harvested table grapes by a ground squirrel. I challenged him/her/it and saw it jump from the grape vine about 2 pm in the afternoon

There are different ways to eliminate ground squirrels. Pest control companies exist that focus on “humane methods” and market these options for concerned gardeners. I would refer anyone interested to follow the advice given by the University of California regarding controlling ground squirrels (http://ipm.ucanr.edu/PMG/PESTNOTES/pn7438.html). Please remember that trapping and releasing an animal to another area is illegal in most states and potentially cruel.