Without more info and with just a quick look, the plant looks deficient in iron.. It doesn't appear to be fusarium as it has maintained its turgidity for the most part (or have the symptoms JUST begun?).. For curiosity's sake, cut open a stem to see if the characteristic brown streaks are working their way around the xylem .. Also, check the limp branch at night to see if it improves as this would point towards fusarium as well. An iron def will cause limp new growth and eventually complete chlorosis as your displaying as well; it will start with new growth as you've also described (less mobile mineral).. So if you slice a stem and don't see the characteristic brown streaking of fusarium then the question is, what's up with your growing conditions, ie. soil ph (this is a big one as it could lock out multiple minerals) feeding schedule, feeding approach (thinking synthetics as you questioned salt damage), watering schedule, light exposure etc..

The fruit itself - again what is the variety name? please include that info in your posts - is yellowish (is it supposed to be yellow or not) and shows signs of BER so likely should have been picked and pitched long ago. Splitting is normally due to water issues of some kind but in this case given the location on the fruit it looks more like cage damage, perhaps from heavy wind. The plant as a whole is in bad shape and looks to have going downhill for some time. It needed an intervention some time ago. It could have been EB or Septoria or grey mold or any one of several other diseases. But in such an advanced stage of decline it is impossible to ID what may have started it or what clues the leaves might have given a couple of weeks ago. The classic leaf symptoms of the common diseases that we use to differentiate the diseases have long since shriveled and died. The only real clue in the photo is the yellowing of the stem sections I see and the fact they are yellow and not black. So if I had to bet on what the original problem was I say the odds favor Early Blight with some nutritional issues thrown in. Sorry I can be more specific but at this stage the plant is a lost cause. Dave

The little brown specks are seeds. When you don't deadhead the flowers the spent blooms will form seed pods, which will pop when they are ripe hence little tiny seeds go everywhere. In order to get more flowers instead of seed pods you need to deadhead the spent flowers. If I were you I would cut all the stems back to about 4 inches long and fertilize the plant with a liquid fertilizer where the middle number is the highest number. The middle number is phosphorus which affects blooming. When you use a fertilizer where the first number is the highest number that causes a lot of foliage growth instead of flowers. Make sure the plant isn't dry when you fertilize it. The plant will look dismal after you cut it back but never fear it will grow back out especially with the addition of the fertilizer. You should fertilize petunias with a liquid fertilizer once a week, but never fertilize them when the soil is dry. Deanna

You can use the finger method to control too little/much watering. At 6-8am for 2-3 weeks, insert a finger into the nearby soil daily to a depth of 4". Determine if the soil feels dry, moist or wet. If it feels dry or almost dry then water but otherwise hold off to prevent development of other issues like fungal infections and root rot. Each time that you water, make a note in a wall calendar. After 2-3 weeks, review the notes in the wall calendar. Determine how often you had to water, on average. Was it every 2 days? 3 days? etc. Then set the sprinkler or drip irrigation to provide from 1 to 1.5 gallons every "x" days. If the temperatures change 10-15F and stay there, consider using the finger method again to see if you need to tweak things. In June or July, you should be increasing the frequency of watering or increase the amt of water per watering. Then in the Fall, you should start reducing the water. As the plants go dormant, you can decrease further and water once a week or once every two weeks depending on local rains. Stop if the soil freezes. Resume watering in the Spring when the soil thaws. When hand watering, never water the leaves; instead, water the soil from the crown where all stems originate from and water outwards. Maintain the area mulched with 2-4" of organic mulch year around (do not use rocks as mulch). Identify what pests may be at work and then take appropriate measures for that type of pest. Many do not require an insecticide per se. Sometimes you can kill them with a hose set to give them a strong shock of water for example. But identify them. After all, an insecticide that is not targeted to kill your type of pest will be wasteful spending and do nothing to the other pests. ;o) Powdery mildew is caused by fungi that thrives in high humidity and dampness so you can try not to over water but if it is due to too much rain then you can't "stop" what started it. I have some PM near a neighbor's pool for example, so nothing I can do about that except put PM resistant plants and occasionally apply anti-PM sprays. A solution of 10% to 30% milk diluted in water can be sprayed weekly to get rid of PM. A different spray with 1 gallon of water 1tbsp of baking soda and a few drops of liquid soap can also be applied weekly. Thinning plants to air flow improves can also help but I would use sprays first (remember to spray the top, bottom of leaves and the stems). Replace mulch with new mulch in heavy infestations. Recreate these spray mixtures weekly. Throw away unused spray liquids. https://www.thespruce.com/baking-soda-for-controlling-powdery-mildew-1402520 https://www.thespruce.com/powdery-mildew-1402500 For pests, the actions to take will be unique to each so identify any pests first. Here is just an example: If you have spider mites, use insecticidal soaps/oils like Safer; use a strong bolt of water from a hose; or use a miticide if it is a large infestation and temperatures are above the level where insecticidal soaps/oils cannot be used. Next, year release predatory mites, lacewings and-or ladybugs a month before the infestation started.