When you take care of your citrus trees properly, they reward you with large, fleshy and appealing fruits.
And caring for the tree means providing the perfect environment right from the seedbed preparation, transplanting, to its entire life.
However, there are numerous citrus diseases and weeds you have to watch out and control. Some insects and plants are almost similar. Thus the knowledge of the correct pesticide for citrus tree is crucial.
And that’s the purpose of this post, to equip you with that knowledge. Because without the right pesticides, the plants won’t develop the healthy leaves and fruits.
Did you know that severe attack of insects and fungi can cause a young citrus plant to die?
That’s why you have to read through this guide. It gives you insight into the effective pesticides to use on your lemon, tangerine and orange trees.
Are you troubled by aphids, scales or curled leaves on your citrus trees? Then I’ve got the solution for you! I’m going to inform you about the right pesticides to use for each type of insect and weeds.
And once we’ve talked on the right insecticides and fungicides, I’ll take you through the right plant growth regulators to boost your citrus blossom.
1. Insecticides for Citrus Tree
Insects are dangerous to crops and citrus are no exception. They can attack all parts of the plant; from the stem, branches, leaves, shoots, and even fruits.
The insects suck the valuable plant liquid, drill through the fruits and attack the stem. That’s why you need the insecticides; to kill the dangerous insects from your crop.
1.1 Aphids and thrips
For instance, when aphids attack the citrus plant, the symptoms appear on the leaves. First, they flock on the leaves and suck out the sap. That causes the puckering and yellowing of the leaves. Next, they drip honeydew, twist and distort. The honeydew causes the development of dark molds on the plant. Eventually, the leaves drop.
And do you know what thrips does to the citrus plant? It causes the leaf buds to shrink, curl and become silver grey. And the fruit grows streaked and scabbed.
Solution to controlling aphids, thrips, and mealywing infestation;
Use the pesticide mixture Emamectin Benzoate+Pyriproxyfen or Beta-cypermethrin+Clothianidin, Spinetoram
On the other hand, scales are also hazardous to your crop. Their presence is announced by the yellowing of the leaves and fruits. The shoots also register irregular growth while the back becomes snowy white. To the tender plant, it causes it to have stunted growth.
Thus when you seek control over orange scale, use insecticides such as Spirotetramat, Sulfoxaflor, Chlorpyrifos or mineral oil.
Rightfully said inchworms are the caterpillars of certain species of moths. An adult inchworm measures an inch. The worms are identified by shades of green, brown, black or yellow on their back. At the sides, they have white or yellow streaks.
The insatiable worms eat the citrus foliage thus leaving behind the tattered appearance of the leaves. Heavy manifestation of the larvae causes complete loss of the plant leaves, thus endangering the plant.
The best time to control the inchworms is shortly after hatching, during their young stage. Use insecticides such as Chlorantraniliprole, Emamectin Benzoate+chlorfenapyr or Emamectin Benzoate+tebufenozide
1.4 Red spider mite
The red spider mite mostly feeds on the leaf underside. But when they attack the citrus plant in large numbers, they flock all over the leaf.
The insect uses its piercing mouth to suck the liquid from the leaves. As a result, the once healthy leaves turn yellowish brown. In the end, they curl and dry up. Furthermore the red spider mite also leaves the silk web on the other parts of the tree.
To manage the red spider, use a mixture of etoxazole+ abamectin, spirodiclofen+abamectin, spirodiclofen+abamectin, fluazinam, and Pyriproxyfen
1.5 Citrus psylla
The citrus psylla is the leading cause of citrus greening disease. They mostly lay eggs at the time when the tree develops new leaves. The pest leads to the twisting of the leaves. Eventually, due to the vicious and waxy honey secreted by the insect, the citrus leaves become dark and moldy.
Solution; controlling the citrus psylla is possible through the use of the pesticides Chlorpyrifos, Clothianidin, Bifenazate, and Sulfoxaflor
The leafminer is easy to distinguish by their snake resembling mine. The leafminers love to feed on the new and tender leaves. In the end, the attacked leaves curl, twist then crumble down. A severe attack on the citrus tree causes stunted growth for the young trees.
Use the pesticide Chlorpyrifos+Abamectin and Chlorantraniliprole to control leafminers.
1.7 Phyllocoptruta oleivora Ashmead( citrus rust mite)
The mites are very tiny yet cause severe damage to citrus fruits. The insects exist in different colors like rust, red, yellow or brown.
Mostly rust mites affect the fruits. The citrus fruit damaged by the rust mite has blemishes on the peels. Depending on the time of damage (summer or spring), the fruit can take the light or dark color.
The leaves of the infected plant become stamped silvery color. Besides they can also become yellow spotted.
To control the disease use the insecticides: Abamectin, Bifenthrin, or Lufenuron
1.8 Citrus blossom midge
Citrus blossom midge is gnat sized flies. Owing to their small size they are very hard to see with the visible eye. But they mostly attack the citrus flowers.
The midge larva resides in the closed flower. As a result, it can cause the flower to distort in shape or fail to open completely. Eventually, such unopened buds crumble to the ground.
Also the flies attack the petals too.
To control the tiny flies, use Beta-cypermethrin + Thiamethoxam and the Deltamethrin
1.9 Bactrocera dorsalis
The fruit fly is slender but has the size of the usual fruit fly. When the female wants to lay eggs, it pokes a hole through the fruit and deposits the eggs inside. At the same time, the laying of the eggs also leaves behind the bacterium which causes the rotting of the fruit.
Within a few days, the eggs hatch, and they then begin to eat the decaying fruit
However, it might be hard to detect early enough the damage the bactrocera dorsalis causes inside the fruit before it spreads outside.
So watch out for signs like discolored spots on the citrus fruit. The patches are the signs of the fly’s sting. Eventually, the fruits will fall before they develop to maturity.
Control the invasion of the insect using Deltamethrin+imidacloprid, Beta-cypermethrin+thiamethoxam and Chlorpyrifos insecticides.
2. Citrus Fungicides
Symptoms of Citrus Fungal Infection and Diseases
Citrus trees are affected by a large number of fungal diseases. You should, therefore, keep watch on the leaves, trunk, shoots, and fruits too.
One of the significant fungal infections that make your citrus fruit unattractive is melanose. The disease causes irregular dark brown spots on the leaves, fruits or shoots. And when test the texture of the affected part; you will notice the bumpy feeling.
Pruning of dead twigs and spraying of the right fungicides named below helps control the disease.
Although melanose doesn’t affect the fruit quality, it discolors and makes the peel quiet ugly. If not taken care of the same fungus will cause the decaying of ripening fruits; stem end rot.
Greasy spot is another fungus disease to watch out. The early signs of the disease include the appearance of the light orange to brownish blister marks on the leaves, mostly on the underside.
The blisters are slightly raised above the leaf surface. In the end, the spots become oily, and the leaves drop. Soon the fruit also discolors
Insect on a citrus tree secretes honeydew on the leaves. Eventually, the leaves blacken, and mold develops, hence the sooty mold.
Have you ever spotted raised irregular outgrowths on your citrus trees? That’s the symptom of a fungal infection is known as scab. It’s common on tangerines, grapefruits, lemons, and sour oranges. Severe cases of diseases lead to the distorted shapes in fruits and leaves. T
To treat scab, use the following fungicides; chlorothalonil, difenoconazole, Polyram, tebuconazole+Trifloxystrobin, pyraclostrobin+Polyram
The tree bark has also not been left behind. Have you ever noticed dark oozing patches on your citrus tree bark? Now that is evidence of the gummosis fungal infection. The fungal infection can spread to the crown and roots too. In advance cases, it causes yellowing, browning, and decaying of leaves.
As the infection intensifies, the back cracks dry and then dies. It then leaves behind a dark sunken citrus canker. The fruit, especially those close to the ground are affected too. They develop brown, tough spots.
To treat gummosis, use the fungicides Carbendazim and thiophanate-methyl
Post-bloom fruit drop
The next critical stage to watch out for the fungal diseases is when the tree flowers. First, you might see water filled wounds on the petals. These lesions might then change color from pink to orange-brown before becoming finally dry and hard.
Such signs are the manifestation of the post-bloom fruit drop. Eventually, the fungal disease causes the young fruit to fall, leading to few or no fruits left on the tree. To control the post-bloom fruit drop, use pyraclostrobin, trifloxystrobin or azoxystrobin fungicides.
The disease mostly affects the leaves and fruits of citrus trees. The leaves bear brown spots and become oily too. At an advanced stage, the fruits and the leaves will drop too. The infection is easily spread by wind-driven rain.
To suppress the infection use copper-based fungicides like copper hydroxide, copper calcium sulphate or copper acetate.
The fungal disease attacks various parts of the citrus tree like leaves, stems, fruits and even the roots. However, it’s straightforward to spot the symptoms of the disease on the leaves and the ripe fruits.
It begins with the appearance of spots on the leaves. The spots appear in shades of black, dark-brown or brown. With time it spreads and covers the whole leaf surface.
As it advances the stem forms cankers, fruits, and the roots rots, the affected fruit develop sunken water-soaked spot.
Fortunately, you can control the Anthracnose disease using the following fungicides;
Mancozeb, pyraclostrobin+Polyram, Tebuconazole+Trifloxystrobin.
You can also use Carbendazim+ Bromothalonil; Azoxystrobin
The disease affects the leaves, fruits, and even the young shoots. If you notice small and a little sunken brown spots on the leaves or fruits, then that’s the brown spot infection. Eventually, it spreads until the whole fruit or leaves develop spots
To prevent the brown spot before it occurs, use the protective fungicides such as mancozeb，Copper hydroxid and Axine copier.
But otherwise, if it has already attacked your citrus tree a systematic application of the following will help;
- Dicarboximide fungicides such as; Procymidone, Iprodione, Tuzet, and prochloraz
- Strobilurin fungicide like; Azoxystrobin, Trifloxystrobin, Pyraclostrobin
3. Citrus Plant Growth Regulators
Here are the common plant growth regulators and their benefits to your citrus trees.
- Gibberellic acid (GA3）
As a plant growth regulator, GA3 helps to delay the over-ripening of the citrus fruit, otherwise called fruit senescence. The timing of the chemical’s application is very crucial for best results.
At the same time when applied at the full bloom, it increases the set of fruits on the plant. On the other hand during storage, the GA3 help to prevent the sour rot in lemons.
However, it is not advisable to apply GA3 to the water or heat stressed the plant. It will lead to an excessive loss of leaves.
So to delay the lemon maturity and the softening of the tangerines, GA3 is the plant growth to use. It helps you to harvest your crops at the right time of the season.
- NAA （Naphthylacetic Acid)
Thinning is essential to the citrus tree. It ensures that you have fruits of the right size and quality. The suckers that could otherwise grow on the stem thereby affecting the fruit quality are discouraged.
That why you need the NAA pre-harvest plant growth regulator, to check on the growth of suckers and improve the fruit size and quality. For optimum result, you have to follow the recommended application label rate at the right day temperature.
4. Citrus Herbicides
Controlling the growth of weeds on your citrus farm is essential. Such unwanted vegetation may be the residing places of pests and insects that affect your crops. Besides they also compete with the plant nutrients and moisture.
Furthermore harvesting of citrus fruits from a weed-infested farm is also tricky. That’s why herbicide use is vital for all citrus farmers.
The herbicides can either be pre-emergence or post-emergence types.
The pre-emergence herbicides are the weed killers applied to the clean soil before any weed or vegetation grows up. Post-emergence is applied to plants that have already grown up.
Here are our recommended citrus herbicides and the range of weeds they control;
This is the herbicide applied before the emergence of any weeds. It’s incorporated into the clean soil. However, you should ensure that you don’t place the herbicide-treated soil close to the citreous roots. Plant the citrus tree such that its roots go deep below the treated soil
Trifluralin helps in eradicating both the perennial and annual weeds. It’s ideal for controlling the Johnson grass on your farm.
It’s the non-selective herbicide applied on the grown weeds. It’s best applied to the plants using the controlled applicator.
Glyphosate is applied at different rates to control both the annual and perennial weeds. It requires the systematic application.
Glyphosate is best applied to the little or vibrantly growing weeds during the flowering stage.
Clethodim belongs to the post-emergence herbicides used on vigorously growing grasses. The rate of the herbicide application per acre is dictated by the type of weed you intend to eliminate from your citrus farm.
For instance foxtails, barnyards and panicums of heights 4 inches or below, requires lower rates. But to control the crabgrass, you need the medium rate of the herbicide per acre.
Other weeds like goosegrass, sprangletop, ryegrass or the lovegrass require higher concentration.
This herbicide is best used when the citrus fruits receive an adequate amount of water. You shouldn’t use it on newly transplanted citrus seedlings till the ground is established and all the cracks sealed.
Pendimethalin, best controls the annual grasses.
Paraquat is anon selective herbicide for controlling weeds. You should use it on the plants with a height of 4 inches or below.
However, take care not to sprinkle it on the citrus tree trunk or leaves. Consequently, consider using tree wraps around the trank for protection.
It’s important to keep a close check on the citrus plantation for the early signs of fungal diseases entrance of insects and pests.
That’s why you have to read through the complete guide about pesticide for citrus trees.
Doing so will enable you to detect at the earliest times any pest attacking your crops.