Bacterial blight symptoms

Bacterial blight symptoms

Why we are seeing bacterial blight symptoms on resistant or immune (cotton) varieties?

Bacterial blight update. Disease appears to be affecting some partially resistant, resistant and immune cotton varieties in Texas High Plains.

The moderate temperatures and wet conditions experienced throughout the High Plains from May to July were conducive for the development of bacterial blight (Fig. 1). An increase in the disease was observed across most of the region with observations of bacterial blight-like symptoms occurring on varieties that had previously been documented as being resistant or immune. 

Initial ratings of a research trial near Plains, Texas, found the disease to be present in most all plots with disease incidence averaging nearly 25 percent. Upon closer examination, the ratings were found to be incorrect resulting from erroneous labeling of plots in the field. This is good news from a production perspective, as the updated disease ratings with correctly labeled plots immune.

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It is interesting to note that bacterial blight symptoms have been and continue to be observed on partially resistant, resistant and immune varieties (Table 1); however, the incidence of these symptoms did not intensify compared to what was observed on susceptible varieties.  We would like to apologize for the errant reporting of disease incidence ratings in early August; however, the fundamental question of “Why we are seeing bacterial blight symptoms on resistant or immune varieties?” remains.

Bacterial blight was also found on FiberMax 1830GLT in a trial near Amherst, and on FM 2484B2F from a field trial in Lubbock. We are continuing to examine the occurrence of disease and hope to better understand the factor(s) that have led to the development of bacterial blight on such varieties.

Currently, the implication of this aspect of the disease on yield is not known.  Boll infections (Fig. 1) were less common than the foliar symptoms.  It is likely that yield of resistant or immune varieties will not be affected; however, it will be important to document fields where bacterial blight was observed this year in order to monitor the disease in subsequent years.

We appreciate all who submitted samples for disease diagnosis.

Please contact Dr. Wheeler (806-746-6101; [email protected]) or Jason Woodward (806-632-0762; [email protected]) with any comments, questions or concerns you may have about bacterial blight in cotton.

 

Figure 1. Bacterial blight symptoms on cotton leaves (top) and bolls (bottom).

Figure 1. Bacterial blight symptoms on cotton leaves (top) and bolls (bottom).

 

 

 

 

 

 

 

 

 

 

 

 

Table 1

Table 1. Updated bacterial blight incidence ratings from a variety trial near Plains, TX exhibiting Bacterial blight on most all varieties throughout the seasonz

Variety or breeding line

Disease incidence (%)

Race 18 resistance rating

5-Aug

26-Aug

16-Sep

BX1531GLT

28

19

14

No data yet

BX1532GLT

20

35

21

No data yet

BX1633GLT

45

80

68

No data yet

BX1634GLT

21

58

53

No data yet

BX1635GLT

7

0

0

No data yet

BX1637GLT

3

1

0

No data yet

DP0912B2RF

16

59

45

Susceptible

DP1311B2RF

6

51

46

Susceptible

DP1321B2RF

70

100

100

Susceptible

DP1359B2RF

7

0

1

Partially resistant

DP1410B2RF

5

1

0

Resistant

DP1441RF

55

72

80

Susceptible

DP1454NRB2RF

93

100

100

Susceptible

DP1538B2RF

16

59

54

No data yet

DP1549B2RF

54

95

100

No data yet

DP1553B2RF

44

88

85

No data yet

DP1555B2RF

35

78

61

No data yet

DP1558NRB2RF

52

80

69

No data yet

FM1320GL

3

10

5

Susceptible

FM1830GLT

0

3

0

Immune

FM2007GLT

0

0

0

Resistant

FM2322GL

33

57

33

Susceptible

FM2334GLT

2

0

0

Immune

FM2484B2F

3

0

0

Immune

NG1511B2RF

26

58

44

Susceptible

NG5007B2RF

35

72

55

No data yet

PHX3003-WRF

19

29

8

No data yet

PHY339WRF

10

0

0

Partially resistant

PHY417WRF

50

75

28

Susceptible

PHY444WRF

15

5

15

No data yet

PHY487WRF

50

80

88

No data yet

PHY495W3RF

52

83

86

No data yet

PHY499WRF

34

51

66

Susceptible

PHY575WRF

0

0

1

No data yet

ST5289GLT

5

1

1

Immune

ST6182GLT

35

61

41

No data yet

MSD(0.05)

38

33

29

 

 

ZVarieties in bold represent those that have been designated as Partially resistant, Resistant or Immune from previous testing.  Differences in disease incidence ratings between varieties within a column greater than the MSD are significantly different.

 

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