Confused? Spot blight, stem blight, bacterial wilt, Fusarium wilt... what's the relationship between all these "blights"?

Spot blight, leaf blight, stem blight, gummy stem blight, damping-off, bacterial wilt, Fusarium wilt... seeing so many "blight" diseases, do you feel your brain has already turned to mush? What's more, many of these diseases share a lot of similarities in their symptoms. For example, between bacterial wilt, Fusarium wilt and damping-off, and between gummy stem blight and Fusarium wilt, how do you tell them apart?

First, let's look at damping-off, bacterial wilt and Fusarium wilt.

What the three diseases have in common:

In the early stages of the disease,

they all wilt during the day (at noon) and recover in the morning and evening.

How the three diseases differ:

(1) Different onset periods

Damping-off

is a common disease at the seedling stage,

mostly occurring in the middle and late stages of seedling raising.

Bacterial wilt

generally occurs at the mature plant stage.

Fusarium wilt

generally occurs at the flowering and fruiting stage.

(2) Different symptom expressions

Damping-off

The seedlings turn yellow and curl up,

at the base of the stem there are initially oval or irregular dark brown lesions,

which gradually wither and rot to death; when the seedling is pulled up by hand,

the stem base separates from the root and breaks easily.

Bacterial wilt

The main symptoms are rapid wilting and death of the plant,

while the stems and leaves remain green

. If you squeeze the browned part of the diseased stem by hand,

a milky white bacterial fluid oozes out.

Fusarium wilt

The disease strikes suddenly, and symptoms include severe spotting, wilting,

or death of leaves, flowers, fruit, stems or the whole plant.

Damping-off (also called seedling death)

mainly harms the stem base or underground roots of seedlings.

Damping-off of watermelon seedlings

Root symptoms of rice damping-off

Initiallyoval or irregular dark brown lesions.

In the early stage of the diseased seedling, it wilts during the day and recovers at night,

the diseased part gradually sinks and constricts,

some gradually turn dark brown,

and finally dry up and die, rarely lodging.

Mildly diseased plantsshow only brown sunken lesions without dying.

When the seedbed humidity is high,

on the diseased part a faint light brown spider-like mold can be seen,

but it is not prominent.

Here you need to note the difference between damping-off and seedling blight,

both are diseases that commonly occur during the seedling-raising period.

Differences:

Seedling blight often occurs after the seedlings emerge and before the true leaves have unfolded,

producing flocculent white mold, with a faster lodging process,

mainly harming the seedling base and stem.

Damping-off mostly occurs in the middle and late stages of seedling raising,

with no flocculent white mold during the disease,

and the plant does not lodge in the course of the disease.

Bacterial wilt and Fusarium wilt

Similarities:

Both are vascular bundle diseases,

and after onset the vascular bundles turn brown.

Tomato bacterial wilt

Watermelon Fusarium wilt

They appear as wilting and withering of the whole plant or part of it; in the late stage of the disease, the diseased plant will wilt and die.

Differences:

(1) Different pathogens

Bacterial wilt is a bacterial disease caused by the rod-shaped bacterium Pseudomonas solanacearum.

Fusarium wilt is a fungal disease caused by Fusarium oxysporum of the genus Fusarium, subphylum Deuteromycotina.

(2) Different symptom expressions

Fusarium wilt generally occurs at the flowering and fruiting stage,

starting from the lower leaves, wilting successively from bottom to top.

Leaf colorgradually fades from green,

from yellow to withered yellow, then turns brown.

Leavesbasically do not fall off, and the whole plant dies.

Stems or stem basesplit longitudinally,

and overflow a yellow-brown gummy substance. ⟧77⟧Diseased roots brown-rot

Brown rot disease; cut the diseased stem lengthwise,

and you can see the vascular bundles at the stem base turn brown.

Under humid conditions,

the surface of the diseased part has white or pink mold-like growth.

Bacterial wilt generally occurs at the mature plant stage; first the top leaves wilt and droop,

then the lower leaves wilt, and finally the middle leaves wilt,

and in some cases the leaves on one side wilt first, or all the leaves of the whole plant wilt at the same time.

The leaves wilt with bacterial wilt and generally do not turn yellow or change color.

With bacterial wilt, after cutting the diseased stem crosswise,

when you squeeze the discolored vascular bundles by hand,

white bacterial fluid overflows,

which is its pathogenic bacteria.

But after Fusarium wilt kills the plant, the leaf color turns yellow,

and no white bacterial fluid seeps out when the cross-section is squeezed.

Gummy stem blight

Gummy stem blight is also called "black rot",

generally occurs on cucurbits,

and when it occurs, its symptoms are similar to those of cucurbit Fusarium wilt.

The biggest difference between the two

is that when gummy stem blight occurs, the vascular bundles do not turn brown.

Specific symptom expressions:

Cucurbit Fusarium wilt can occur from the seedling stage to the mature plant stage.

When seedlings are affected, the cotyledons turn yellow and lose their luster,

the cotyledons or the whole plant wilt, and the stem base turns brown, constricts and causes damping-off.

Affected plants initially show:

some leaves or the leaves on one side of the plant

wilt and droop at noon, as if short of water,

but the wilted leaves recover in the morning and evening,

then the wilted leaves keep increasing,

gradually spreading over the whole plant, causing the whole plant to die.

The main vine constricts, exudes gum, or develops yellow-brown longitudinal cracks,

and cutting the diseased stem lengthwise shows the vascular bundles turn brown;

when humidity is high, the diseased part has white or pink mold-like growth.

Cucurbit gummy stem blight mainly harms stems, vines and leaves,

mostly occurring at the mature plant stage.

When stems and vines are affected,

oval to spindle-shaped lesions appear at the nodes,

the diseased part is grayish white,

with amber-colored gelatinous substance overflowing,

then the diseased part turns yellow-brown,

and after drying and shrinking, small black dots are scattered on it,

finally the diseased part splits longitudinally into a tangled hemp-like appearance.

But

Vascular bundles do not turn brown (this is the difference from Fusarium wilt)，

In severe cases, it causes "stem rot."

Leaf infection

The lesions are round or irregularly round,

dark brown or with concentric rings.

Lesions occurring on the leaf margin are generally arc-shaped.

Those occurring in the middle of the leaf are nearly round, thin-papery, light brown large spots.

Now let's look at the other three diseases,

they also carry the word "blight,"

let's see what symptoms they show.

Stem blight

It mainly affects stems and fruits, and also affects leaves and petioles.

Wounds on the stem make it susceptible to this disease.

The lesions are initially oval, brown, sunken and canker-like,

then extend up and down the stem to the whole plant.

In severe cases, the diseased part turns dark brown and dry-rots,

and can invade the vascular bundles.

When fruits are infected, it infects green or red fruits.

Initially small grayish-white spots,

then as the lesions expand they become sunken and turn brown,

grow black mold, and cause rot.

When leaf lesions continue to expand, the leaf margins curl,

and finally the leaves dry up or the whole plant dies.

Leaf spot blight

The pathogen mainly infects leaves, and also affects stems.

For example, tomato leaf spot blight:

At the initial stage, water-soaked small round spots appear on the underside of leaves,

then chlorotic spots appear on the leaves.

In severe cases, the leaves gradually turn yellow and wither,

the plant ages prematurely, causing early defoliation.

Leaf blight

It mainly occurs on leaves

Leaf blight mostly infects starting from the leaf margin and leaf tip.

The lesions are irregular, from small to large, red-brown to gray-brown,

the lesions merge into large blighted spots, with a clear boundary between diseased and healthy tissue.

Later, some small black dots form on the lesions.

In summary, the causes of wilting are numerous and varied,

but as long as the symptoms are clearly identified, treating the root cause is the key.

We should try to provide plants with a relatively ventilated environment,

and secondly, based on whether it is caused by fungal infection or pests and diseases,

using the right fungicide and insecticide is the key.

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